Robert J. Grass, MD
Internal Medicine Physician · Fond Du Lac, WI
Robert J. Grass, MD is an internal medicine physician with a practice address in Fond Du Lac, Wisconsin, and NPI 1689665093, issued on Nov 3, 2005. Check the license (Wisconsin 43234, as entered in NPPES) on the Wisconsin Medical Examining Board; the Medicare figures below come from public CMS files.
- Name
- Robert J. Grass
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- 43234 WI
Self-reported in NPPES; status is on the state search - Practice location
- 420 E Division St, Fond Du Lac, WI 54935
- Phone
- (920) 926-8615
- Enumerated
- Nov 3, 2005
- Record last updated
- Oct 18, 2024
- Medicaid ID
- 34090300 WI
- Medicare enrollment
- Enrolled (PECOS I20100521000337); accepts Medicare assignment
- Medical or professional school
- Medical College Of Wisconsin, 1997
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 2,078 in Wisconsin → Look up another NPI →
Also registered at 420 E Division St
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Elizabeth Berenz, FNP-BCFamily Nurse Practitioner1619386885
- Melissa Berggren, PA-CPhysician Assistant1639377617
- Louann Biddick, NPNurse Practitioner1770566721
- Jennifer Bissell, MDFamily Medicine Physician1316146962
- Tiffany Boelk, APNPNurse Practitioner1700459690
- David Bowman, M.D.Cardiovascular Disease Physician1962492397
Verify Robert J. Grass in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWisconsin Medical Examining Board
Search for license 43234Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
83% more Medicare Part D claims than the average internal medicine physician in 2024
5,802 Medicare Part D claims for 346 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 11% of claims. 132 claims were for opioids.
Most prescribed
- Atorvastatin Calcium356 claims
- Amlodipine Besylate218 claims
- Omeprazole181 claims
- Simvastatin174 claims
- Lisinopril173 claims
- Losartan Potassium168 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.
Industry payments in 2024: $16.65
1 payment: education; the largest payer was E.R. Squibb & Sons, L.L.C. The 50,334 providers of this specialty with any payment received $1,303.06 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Bills Medicare through one group practice
- Agnesian Healthcare IncFond Du Lac, WI
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Robert J. Grass among 2,078 internal medicine physician records in Wisconsin
Robert J. Grass, MD is one of 2,078 internal medicine physician records with a practice address in Wisconsin. 70% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2005, is newer than 0% of them.
- NPI issued2005 · 0% of these records are older, 91% newer
- In a Medicare fileYes · 70% of these records are
- In the CMS Doctors and Clinicians fileYes · 53% of these records are
- Graduated1997 · median 2002 among the 1,098 with a school on file
- Record last updated2024 · 55% 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 Wisconsin practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
19 internal medicine physician records list a practice address in Fond Du Lac
They are 19 of the 1,312 NPPES records with a practice address in Fond Du Lac, and 2,078 internal medicine physician records in Wisconsin.
All 2,078 in Wisconsin → Every provider in Fond Du Lac → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- E Ayala, MDFond Du Lac, WI 549351821089541
- Oliver Clements, MDFond Du Lac, WI 549351184615429
- Punit Kumar, MDFond Du Lac, WI 549351144271990
- Madhulika Lall, MDFond Du Lac, WI 549351821009838
- Gabriel Litman, MDFond Du Lac, WI 549351184731630
- Joseph Marik, MDFond Du Lac, WI 549351710969860
- Jay Muller, MDFond Du Lac, WI 549351053305961
- Radhika Raj, MDFond Du Lac, WI 549351669467072
Common questions
What is Robert J. Grass, MD's NPI number?
Robert J. Grass, MD's National Provider Identifier (NPI) is 1689665093, issued on Nov 3, 2005. An NPI identifies a provider in billing; it is not a license.
Where is Robert J. Grass, MD located?
The NPPES record lists a practice address at 420 E Division St, Fond Du Lac, WI, 54935. Phone: (920) 926-8615. Providers update this record themselves, so call before visiting.
How can I verify Robert J. Grass, MD's license?
NPPES lists Wisconsin license number 43234, as entered by the provider. Search the Wisconsin Medical Examining Board at https://dsps.wi.gov/Pages/BoardsCouncils/MEB/Default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Robert J. Grass, MD prescribe under Medicare Part D?
In 2024, Robert J. Grass, MD had 5,802 Medicare Part D claims for 346 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.