Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.

Dr. Ronald Keith Willenborg, MD

Individual provider Internal Medicine Physician · NPI 1801897897

Dr. Ronald Keith Willenborg, MD is an Internal Medicine Physician in Upper Montclair, New Jersey. Practices as a sole proprietor. Licensed in New Jersey.

Licensed in
NJ
In the registry since
2005
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

See every abbreviation used in this directory →

Practice location Address checks out

543 Valley Rd Ste 4
Upper Montclair, NJ 07043-1844
Phone: (973) 746-6466
Fax: (973) 746-0312
Show map & directions

Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Internal Medicine Physician (primary) Taxonomy 207R00000X · Licence 25MA03592100 (NJ)

Record details

NPI number1801897897
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorYes
NPI enumeratedAugust 2, 2005
Last updated in NPPESJuly 14, 2010
Mailing address543 Valley Rd Ste 4, Upper Montclair, NJ 07043-1844