The CMS National Plan and Provider Enumeration System currently lists 7,862 Internal Medicine Physician providers with a primary practice address in Massachusetts, all registered under the Internal Medicine NUCC taxonomy branch. Each clinician on this roster selected Internal Medicine Physician as their primary taxonomy at NPI enrollment — a self-reported classification that is updated whenever the provider files a correction with CMS. The count excludes organizations (group practices, hospitals, clinics operate under separate NPIs) and excludes providers who chose a different primary specialty even if they practice Internal Medicine Physician part-time. Every figure is drawn from the federal National Provider Identifier Registry (CMS NPPES) — more than 7 million providers, maintained since May 2007, with 2023 Medicare Part D data — and, according to CMS, can be searched, compared, and traced in our methodology.

At 7,862 enrolled providers, Internal Medicine Physician in Massachusetts is a very well-covered market — that matters for search-radius decisions, because patients in Massachusetts outside the largest metros often need to broaden to adjacent cities to find a local Internal Medicine Physician clinician. The directory below is paginated 50 providers at a time (158 pages total) and is sorted alphabetically by last name, so scanning for a specific practice usually goes faster than scrolling; on the provider detail page you'll find the full NPPES record including address, phone, credentials, and any published Medicare Part D prescribing activity for 2023.

Before contacting anyone on this list, verify the practice is still at the address shown — NPPES refreshes monthly, but providers who have relocated, retired, or changed employers may not have filed an NPI update yet. Important: PlainDoctor is a directory of publicly available CMS government data covering Internal Medicine Physician providers in Massachusetts, not a quality ranking, a board-certification verifier, or medical advice. Always confirm credentials through the NPPES NPI Registry, the Massachusetts medical board, and — where relevant — the ABMS, AOA, or the specialty's primary certifying body before making any clinical decision. Nothing on this page substitutes for a conversation with a licensed clinician.