RIVERSIDE RADIOLOGY MEDICAL GROUP, INC.
NPI 1851694699
Radiology - Diagnostic Radiology in Mill Valley, CA
About Riverside Radiology Medical Group, Inc. NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
RIVERSIDE RADIOLOGY MEDICAL GROUP, INC. (NPI 1851694699) is a healthcare organization registered as a diagnostic radiology in Mill Valley, California and active in the NPI registry since December 2010. The organization lists Donald R. Massee, President, as its authorized official.
NPPES Registry Identity
Specialties & Licenses
Group Practice 1
Medicare Participation & PECOS CMS
Medicare enrollment and the clinicians who bill Medicare through this organization, from CMS.
Medicare Enrollment Status
Enrolled in Medicare (PECOS)
Riverside Radiology Medical Group, Inc. is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).
Clinicians Billing Medicare Through This Organization
35Medicare enrollment records show 35 clinicians reassign Medicare billing to Riverside Radiology Medical Group, Inc., which bills Medicare for the services they deliver. Listed here are the 20 practicing nearest to this location.
Clinicians by Medicare Specialty 3
Nearest to this location (20)
See all 35Loma Linda, CA 92354
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is Riverside Radiology Medical Group, Inc.'s NPI number?
The NPI number for Riverside Radiology Medical Group, Inc. is 1851694699. It was assigned to this organization in the NPPES registry on December 17, 2010.
Where is Riverside Radiology Medical Group, Inc. located?
Riverside Radiology Medical Group, Inc. is located at 338 Lowell Ave, Mill Valley, CA 94941. The listed phone number is (559) 455-4041.
What is Riverside Radiology Medical Group, Inc.'s specialty?
The primary specialty registered for this NPI is Radiology, specializing in Diagnostic Radiology, with taxonomy code 2085R0202X.
Is Riverside Radiology Medical Group, Inc. enrolled in Medicare?
Yes. Riverside Radiology Medical Group, Inc. is registered in the Medicare PECOS enrollment system.
How many clinicians bill Medicare through Riverside Radiology Medical Group, Inc.?
According to the CMS Revalidation Reassignment List (October 2026 release), 35 clinicians in 3 Medicare specialties reassign their Medicare billing to Riverside Radiology Medical Group, Inc.. A reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for the clinician's services. The largest specialties are Diagnostic Radiology (32), Interventional Radiology (2) and Nuclear Medicine (1). Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
When was this NPI record last updated?
The NPPES record for Riverside Radiology Medical Group, Inc. was last updated on December 17, 2010. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 15 years ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.
# Riverside Radiology Medical Group, Inc. · NPI 1851694699
Diagnostic Radiology organization in Mill Valley, California. Organization record, active in the CMS NPPES registry since December 17, 2010.
## Identity
- **NPI:** 1851694699 (Entity type: Organization)
- **Enumerated:** December 17, 2010
- **Primary specialty:** Radiology - Diagnostic Radiology · taxonomy 2085R0202X
- **Organization subpart:** No
- **Authorized official:** Donald Massee, PRESIDENT
## Practice location
- **Address:** 338 LOWELL AVE, Mill Valley, CA 94941-3845
- **Phone:** (559) 455-4041 · **Fax:** (770) 666-9102
## Medicare
- **Medicare:** Enrolled in Medicare (PECOS)
- **Clinicians billing through this organization:** 35 clinicians in 3 Medicare specialties reassign Medicare billing to this organization (form CMS-855R); largest: Diagnostic Radiology (32), Interventional Radiology (2), Nuclear Medicine (1); [full list](https://npiprofile.com/npi/1851694699/clinicians) · CMS Revalidation Reassignment List, October 2026 release
## Record status
- **NPPES last updated:** December 17, 2010
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Source: [NPI Profile](https://npiprofile.com/npi/1851694699) · Data from the CMS NPPES public registry.