
Mark Guelzow, MD
Family Medicine
Highlights
Languages
- English
Gender
MaleLocations
- Internal & Family Medicine, Smithtown
- 373 NY-111, Suite 14, Smithtown, NY 11787
- Get Directions
- phone: 631-265-0050
- fax: 631-265-0204
Expertise
Education
- Residency: St. Joseph's Hospital, Family Medicine, 2019
- Medical School: St. George's University School of Medicine, 2016
Board Certifications
- Family Medicine: American Board of Family Medicine, 2019
Insurance
- Aetna
- Aetna Medicare PPO
- Affinity
- Affinity Essential
- Affinity Exchange
- Affinity Medicaid
- Affinity Medicare
- American Plan Administrators PPO
- Anthem
- Anthem Child Health Plus
- Anthem Essential Plan 1 & 2
- Anthem Essential Plan 3 & 4
- Anthem Medicaid and Individual
- Anthem Medicare
- Beechstreet
- Blue Cross Mcd Hmo
- Blue Cross Medicaid
- Centivo
- Cigna
- Cigna Medicare
- Coventry Health Care
- Elderplan
- Elderplan Medicaid
- Emblem
- Emblem HIP
- Emblem Medicaid
- Emblem Medicare
- Fidelis
- Fidelis Health Exchange
- Fidelis Medicaid
- Fidelis Medicare
- First Health
- GHI
- GHI CBP NY City Employee
- GHI CBP PPO EPO
- GHI HMO
- GHI Medicare Choice PPO/Value Options
- GHI NYS NYC Value Options
- GHI PPO EPO
- HCP Child Health Plus
- Health First
- HEALTH FIRST EP 3&4
- Health First Medicaid
- Health First Medicaid HARP EP 3&4
- Health First Medicare
- HEALTH FIRST RISK EP 3&4 ALT
- Health First Risk Medicaid HARP EP 3&4 Alternate Plan
- Healthsmart Benefit Solutions
- HIP
- HIP Child Health Plus
- HIP Hcare Partners Essent Pl 1&2
- HIP Hcare Partners Essential 3&4
- HIP Hcare Partners HMO
- HIP Hcare Partners Medicaid
- HIP Hcare Partners Medicare HMO
- HIP Hlth Essential Pl 1 & 2
- HIP Hlth Essential Pl 3&4
- HIP HMO POS
- HIP Medicaid
- HIP Medicare HMO
- HIP Medicare PPO
- HIP NY City HMO
- HIP PPO EPO
- HIP Somos Child Health Plus
- HIP Somos Essential Plan 1&2
- HIP Somos Essential Plan 3&4
- HIP Somos Medicaid/HARP
- Humana
- Humana Medicare
- Local
- Local 1 Bricklayers Magnacare
- Local 1102 Magna
- Local 1205
- Local 1298 Magna
- Local 138 Operating Engineers Magna
- Local 1500
- Local 1964
- Local 210 Retiree Grp Magna
- Local 210 Unity Welfare Fund
- Local 25 Ibew Magna
- Local 272 Welfare Fund Magna
- Local 29 Blasters & Drillers & Minors
- Local 3 Magna
- Local 30 Trust Fund Engineers Magna
- Local 338 Magna
- Local 342 50 Magna
- Local 342 Insurance Trust Magna
- Local 361 Magna Care
- Local 381 Magna
- Local 40 Iron Workers
- Local 463 Health Fund
- Local 522
- Local 66 Magna
- Local 6A Cement And Concrete
- Local 802 Musicians
- Local 803 Ibt Health And Welfare Fund Inc.
- Local 804
- Local 806 Bridge Painters - Alicare
- Local 810
- Local 810 Union Wire Metal
- Local 812 Magna
- Local 888 Magna
- Magna Direct Plus
- Magna Preferred PPO
- Medicaid
- Medicaid Out Of State
- Medicare
- Medicare Railroad
- Meritain Health
- Meritain Health Aetna PPO
- Molina
- Molina Exchange
- Molina Medicaid
- Multiplan
- Optum Health/Blue Cross
- Oscar
- Oscar Health Exchange
- Other Medicaid
- Other Medicare
- Oxford
- Oxford Bh
- Oxford Medicare
- Partners Health Plan
- Partners Health Plan Medicare
- Secure Horizon Mcr Complete PPO
- Three Rivers
- Three Rivers Provider Network
- Tricare Champus
- UMR
- UMR UHC Salt Lake City
- United HC Choice Plus POS
- United HC Community Child Health Plus
- United HC Community Medicaid
- United HC Essential Pl 1 & 2
- United HC Essential Pl 3&4
- United HC Exchange
- United HC HMO POS
- United HC Medicare HMO
- United HC Medicare PPO
- United HC Narrow Network
- United Hc Nexus ACO R
- United HC NexusACO OA
- United HC PPO
- United HC PPO Empire Plan
- United HC PPO EPO Indemnity
- United HC Speech
- United Health Plus PPO
- United Healthcare
- United Healthcare Medicaid
- United Healthcare Medicare
- United Healthcare Mpn
- VNS Choice
- Vns Choice Medicare Replacement
- Wellcare
- Wellcare Medicaid
- Wellcare Medicare
- World Trade Ctr Fund
Ratings & Reviews
4.9 out of 5
368 ratings, 53 reviewsThe Patient Satisfaction Rating is an average of all responses to the care provider related questions shown below from our survey. Patients that are treated in outpatient or hospital environments may receive different surveys, and the volume of responses will vary by question.
- 5 out of 5 starsReviewed on 1/27/2026
I couldn't have asked for a better doctor.
- 5 out of 5 starsReviewed on 1/23/2026
A wonderful experience
- 5 out of 5 starsReviewed on 1/18/2026
I love my doctor he is absolutely the best
- 5 out of 5 starsReviewed on 1/11/2026
Dr Guelzow is the best
- 5 out of 5 starsReviewed on 1/10/2026
He is very thoughtful and considerate and cares about my problems
- 5 out of 5 starsReviewed on 1/2/2026
Excellent care and attention to my concerns. Greatly appreciate the doctor taking time to see me given unscheduled visit.
- 5 out of 5 starsReviewed on 12/31/2025
Dr Guelzow is the best primary I've ever had. Very attentive, personal, seems to refresh his memory on the case before joining. Truly, I'd follow this Dr wherever he goes. 10/10 doc
- 5 out of 5 starsReviewed on 12/28/2025
My doctors office is excellent. [...]
- 5 out of 5 starsReviewed on 12/14/2025
Excellent physician. Found hernia during the exam. Thankful.
- 5 out of 5 starsReviewed on 12/7/2025
Very engaging and kind
- 5 out of 5 starsReviewed on 12/6/2025
Relaxed atmosphere. Thorough and clear explanations.
- 5 out of 5 starsReviewed on 11/25/2025
Dr. Guelzow always has the necessary info from other physicians I see knows well about coordinating care.
- 5 out of 5 starsReviewed on 11/20/2025
Would definitely recommend
- 5 out of 5 starsReviewed on 11/12/2025
Very considerate of my feelings due my wife's recent passing
- 5 out of 5 starsReviewed on 11/12/2025
Dr. Guelzow was excellent. My visit was a pleasure & I was well taking care off .
- 5 out of 5 starsReviewed on 11/11/2025
I like Dr. Guelzow very much. He is kind, understanding, always upbeat, and very smart.
- 5 out of 5 starsReviewed on 11/10/2025
Having Dr. Guelzow as my PCP has been awesome. He has guided me through my medical issues. He urged me to get a Colonoscopy which lead to the discovery of Follicular Lymphoma. The short version is Dr. Guelzow saved my life.
- 5 out of 5 starsReviewed on 11/5/2025
Dr. Guelzow is absolutely wonderful!
- 5 out of 5 starsReviewed on 10/11/2025
Doctor is excellent at explaining whatever I have questions about
- 5 out of 5 starsReviewed on 9/24/2025
I definitely felt I was getting good care.
- 5 out of 5 starsReviewed on 9/18/2025
He always takes the time to listen to my concerns . He is never rushed .
- 5 out of 5 starsReviewed on 9/18/2025
Kind and courteous advice.
- 5 out of 5 starsReviewed on 9/18/2025
Have recommended him to family and friends
- 5 out of 5 starsReviewed on 9/12/2025
Dr. Guelzow Is patient and thorough, a great communicator, very kind and friendly as well.
- 5 out of 5 starsReviewed on 9/10/2025
Dr Guelzow answered all my questions
- 5 out of 5 starsReviewed on 9/10/2025
Always helpful and listens to concerns. Listens and responds with a calm manner
- 5 out of 5 starsReviewed on 9/7/2025
Dr Guelzow is attentive, thorough, and informative. His manner gives me a feeling of confidence in his ability to diagnose & treat my medical issues.
- 5 out of 5 starsReviewed on 9/2/2025
Knowledgeable and good listener very pleased with care given.
- 5 out of 5 starsReviewed on 8/19/2025
After having [...] who I miss terribly I have adjusted and like Dr. Guelzow.
- 5 out of 5 starsReviewed on 8/18/2025
I was very impressed with Dr. Guelzow. He is now my primary care physician.
- 5 out of 5 starsReviewed on 8/16/2025
My Doctor is efficient and extremely knowledgeable about any medication that I am taking. He takes the time to explain the good and the bad. He makes suggestions if he's concerned about something
- 5 out of 5 starsReviewed on 8/6/2025
I couldn't be more pleased with how my concerns were addressed. Dr. Mark Guelzow is a very caring doctor and a great listener!
- 5 out of 5 starsReviewed on 8/4/2025
Dr. Guelzow was very kind and thorough. I really appreciate the time he spent with me during my appointment. Thank you!
- 5 out of 5 starsReviewed on 8/2/2025
Dr Guelzow is always cheerful and responsive to any concerns or questions I may have. He clearly explains risks and benefits of any procedures he discusses. He is also very thorough and does not rush me.
- 5 out of 5 starsReviewed on 8/1/2025
The best MD I have ever had!
- 5 out of 5 starsReviewed on 7/31/2025
Good
- 5 out of 5 starsReviewed on 7/20/2025
Doctor Guelzow [...] has always been pleasant, friendly, concerned and efficient. He has a manner that puts the patient at ease and makes them feel valued as a human being.
- 5 out of 5 starsReviewed on 7/17/2025
Dr. Guelzow listens to any questions I have and explains in detail my care.
- 5 out of 5 starsReviewed on 7/1/2025
Dr. Guelzow always takes time with you. Never feel rushed.
- 5 out of 5 starsReviewed on 6/27/2025
I had a great appointment and touch based on anything I was concerned about, always a pleasant experience!
- 5 out of 5 starsReviewed on 6/26/2025
Dr. Guelzow listen to my questions and answered concerns that I had
- 5 out of 5 starsReviewed on 6/24/2025
The doctor was thorough in his examination of me. Explained the treatment and concerns.
- 5 out of 5 starsReviewed on 6/14/2025
Already have recommended Dr. Guelzow to my sons and wife.
- 5 out of 5 starsReviewed on 6/7/2025
Good experience
- 5 out of 5 starsReviewed on 5/23/2025
Dr Guelzow was very efficient answered my question and listened to all I had to day
- 5 out of 5 starsReviewed on 5/18/2025
I can't see how I would want to see any other primary care providers.
- 5 out of 5 starsReviewed on 5/10/2025
Gave me time to explain my problems and what I should do to solve them
- 5 out of 5 starsReviewed on 5/9/2025
Provider listens, assesses, recommendations have always been very good (when a specialty provider is necessary).
- 5 out of 5 starsReviewed on 5/7/2025
Dr. Guelzow is wonderful!
- 5 out of 5 starsReviewed on 5/4/2025
Dr. Guelzow is a very good doctor. He is very kind very thorough and tries to be as understanding of my fears as possible. He is always cheerful and does a good job.
- 5 out of 5 starsReviewed on 4/27/2025
Dr. Guelzow listened very carefully to my concerns and offered me thoughtful recommendations
- 5 out of 5 starsReviewed on 4/24/2025
Dr. Guelzow is very patient does not rush answers all questions and concerns.
- 5 out of 5 starsReviewed on 4/18/2025
He truly cares about my wellbeing and has guided me in the right direction.