Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

John M Wallmark, M.D.

Hematology & Oncology Physician in Rockville, MD · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1689755365

Verified

See something wrong? Report a correction

Registry record

Entity type Individual (Type 1)

Name John M Wallmark

Credential M.D.

Sex Male

Practice address 9707 Medical Center Dr, Suite 300, Rockville, MD, 20850

Phone (301) 424-6231

Fax (301) 294-4648

Enumeration date Oct 18, 2006

Last updated in NPPES Aug 1, 2012

Taxonomy & licenses

207RH0003X Hematology & Oncology Physician Allopathic & Osteopathic Physicians · License D0053177 (MD) Primary

MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

Other identifiers

Identifier	Type	State	Issuer
40453510	Medicaid	MD	-

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

Read the full guide → Validate an NPI →

Frequently asked questions

Is this the official NPI registry?

No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.

What specialty is John Wallmark?

John Wallmark is registered in NPPES with the primary taxonomy of Hematology & Oncology Physician. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

Other providers at this practice address

Browse all →

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2012-08-01.