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

Mr. Gregory Roger Grenier, DO

Individual provider Orthopaedic Surgery Physician · NPI 1134512593

Mr. Gregory Roger Grenier, DO is an Orthopedic Surgery in Billings, Montana. Qualified in 2015, 11 years ago. Practices with Catholic Health Initiatives Colorado, a 1,266-clinician group, works from 2 locations and accepts Medicare assignment. Licensed in Colorado and Montana.

Years since qualifying
11
Licensed in
CO, MT
In the registry since
2015
Specialties on file
2
What do these letters mean?
DO — Doctor of Osteopathic Medicine
A fully licensed physician, trained like an MD with additional musculoskeletal training. Equivalent practice rights in all 50 states.

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Practice location Address checks out

2900 12th Ave N Ste 140W
Billings, MT 59101-7507
Phone: (406) 238-6726
Fax: (406) 272-3395
Show map & directions

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

Additional practice locations (1)

  • 1 Mercado St Ste 202, Durango, CO 81301-7307 — (970) 764-9400

Specialties & licences

Orthopaedic Surgery Physician (primary) Taxonomy 207X00000X · Licence 98833 (MT)
Orthopaedic Surgery Physician Taxonomy 207X00000X · Licence DR.0070117 (CO)

Record details

NPI number1134512593
Entity typeIndividual (Type 1)
GenderMale
Credentials DO
Sole proprietorNo
NPI enumeratedMarch 10, 2015
Last updated in NPPESJanuary 6, 2023
Certification dateJanuary 6, 2023
Mailing address2900 12th Ave N Ste 140w, Billings, MT 59101-7507

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyORTHOPEDIC SURGERY
Medical schoolOTHER
Graduated 2015 (11 years in practice)
Group practice Catholic Health Initiatives Colorado — 1266 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount

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