Ronald Willenborg, M.D.
NPI 1801897897 · Internal Medicine Physician · Upper Montclair, NJ
Enrolled with Medicare as Practitioner - Internal Medicine · source: CMS PECOS Public Provider Enrollment (2026.04.01)
Ronald Willenborg, M.D. is a Internal Medicine Physician provider in Upper Montclair, NJ (NPI 1801897897).
Provider details
- NPI number
- 1801897897
- Entity type
- Individual
- Primary specialty
- Internal Medicine PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- Yes
- License
- 25MA03592100 (NJ)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
20 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
1 documented practice location
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
Practice location
Mailing address
Registry dates
- Enumerated
- 2005-08-02
- Last updated
- 2010-07-14
Frequently asked questions
- What is Ronald Willenborg's NPI number?
- Ronald Willenborg's National Provider Identifier (NPI) is 1801897897, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is Ronald Willenborg's specialty?
- Ronald Willenborg is listed in the NPPES registry with a primary specialty of Internal Medicine Physician (Allopathic & Osteopathic Physicians).
- Where is Ronald Willenborg located?
- Ronald Willenborg's practice location on file with NPPES is 543 Valley Rd Ste 4, Upper Montclair, NJ 07043-1844.
- What is Ronald Willenborg's phone number?
- The practice phone number listed in the NPPES registry for Ronald Willenborg is (973) 746-6466.
- Does Ronald Willenborg accept Medicare?
- Ronald Willenborg is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is Ronald Willenborg's NPI active?
- Yes — Ronald Willenborg's NPI (1801897897) is active in the NPPES registry as of the last update on 2010-07-14.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.