John Walker, D.O.
Internal Medicine Physician · Portland, ME
John Walker, D.O. is an internal medicine physician with a practice address in Portland, Maine, and NPI 1851737811, issued on May 17, 2013. Check the license (Maine DO2640, as entered in NPPES) on the Maine Board of Licensure in Medicine; the Medicare figures below come from public CMS files.
- Name
- John Walker
- Credential
- D.O.
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- DO2640 ME
Self-reported in NPPES; status is on the state search - Practice location
- 22 Bramhall St, Portland, ME 04102
- Phone
- (207) 662-6562
- Enumerated
- May 17, 2013
- Record last updated
- Jun 21, 2016 (not updated in 10 years: call before relying on the address or phone)
- Medicare enrollment
- Enrolled (PECOS I20160822001883); accepts Medicare assignment
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 597 in Maine → Look up another NPI →
Also registered at 22 Bramhall St
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Jessica Abbatiello, NP-CFamily Nurse Practitioner1871811737
- Ruslan Abdukalikov, DOAnesthesiology Physician1831694793
- Tod Abrahams, M.D.Diagnostic Radiology Physician1538231642
- Joshua Abrams, PA-CSurgical Physician Assistant1932832128
- Christopher Abruzzese, D.OAnesthesiology Physician1558789305
- Haley Acker, PA-CPhysician Assistant1972167377
Verify John Walker in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMaine Board of Licensure in Medicine
Search for license DO2640Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
70% fewer Medicare Part D claims than the average internal medicine physician in 2024
948 Medicare Part D claims for 482 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 18% of claims.
Most prescribed
- Peg 3350-Electrolyte307 claims
- Omeprazole155 claims
- Carvedilol59 claims
- Pantoprazole Sodium55 claims
- Gavilyte-N43 claims
- Budesonide Dr23 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Bills Medicare through one group practice
- MainehealthBiddeford, ME
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
John Walker among 597 internal medicine physician records in Maine
John Walker, D.O. is one of 597 internal medicine physician records with a practice address in Maine. 77% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2013, is newer than 74% of them.
- NPI issued2013 · 74% of these records are older, 23% newer
- In a Medicare fileYes · 77% of these records are
- In the CMS Doctors and Clinicians fileYes · 62% of these records are
- Graduated2013 · median 2005 among the 369 with a school on file
- Record last updated2016 · 60% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a Maine practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
145 internal medicine physician records list a practice address in Portland
They are 145 of the 6,022 NPPES records with a practice address in Portland, and 597 internal medicine physician records in Maine.
All 597 in Maine → Every provider in Portland → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Elizabeth Ackerson, MDPortland, ME 041021912920117
- Ari Berman, MDPortland, ME 041021225015829
- Kirsten Berman, M.D.Portland, ME 041021043280431
- Nananda Col, MDPortland, ME 041021104870377
- Heidi Deblock, M.D.Portland, ME 041021922095892
- Kathleen Fairfield, M.D.Portland, ME 041021992744353
- Steven Hess, MDPortland, ME 041021427099498
- Rabee Kiwan, MDPortland, ME 041021992784938
Common questions
What is John Walker, D.O.'s NPI number?
John Walker, D.O.'s National Provider Identifier (NPI) is 1851737811, issued on May 17, 2013. An NPI identifies a provider in billing; it is not a license.
Where is John Walker, D.O. located?
The NPPES record lists a practice address at 22 Bramhall St, Portland, ME, 04102. Phone: (207) 662-6562. Providers update this record themselves, so call before visiting.
How can I verify John Walker, D.O.'s license?
NPPES lists Maine license number DO2640, as entered by the provider. Search the Maine Board of Licensure in Medicine at https://www.maine.gov/md/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does John Walker, D.O. prescribe under Medicare Part D?
In 2024, John Walker, D.O. had 948 Medicare Part D claims for 482 beneficiaries; the average among internal medicine physician prescribers was 3,176. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.