| Odackal, Namrita DO | SVH Neonatology | (406) 237-7076 |
| Ogger, Kelly LCSW | Yellowstone Boys & Girls Ranch | (406) 655-2100 |
| Okamura, Daryl MD | SVHC Fortin Pediatric Specialty Clinic | (406) 237-5300 |
| Oldenburg, Lee LCPC | Oldenburg Counseling, PC | (406) 245-4446 |
| Olds, Jenna FNP | SVHC Billings Transitional Care | (406) 237-8282 |
| Oley, Erin FNP | Beartooth Billings Clinic | (406) 446-2345 |
| Oley, William MD | Beartooth Billings Clinic | (406) 446-2345 |
| Olivo, Elizabeth DNP | Planned Parenthood of Montana - Helena | (406) 446-7676 |
| Olivo, Elizabeth DNP | Planned Parenthood of Montana - Missoula | (406) 728-5490 |
| Olivo, Elizabeth DNP | Planned Parenthood of Montana - Great Falls | (406) 454-3431 |
| Olivo, Elizabeth DNP | Planned Parenthood of Montana - Billings Heights | (406) 869-5040 |
| Olivo, Elizabeth DNP | Planned Parenthood of Montana - Billings West | (406) 656-9980 |
| Olson, Catherine OD | Ophthalmic Associates of Billings, LLC | (406) 256-6000 |
| Onstad , Daysi LCPC | Summit Therapy Center PC | (406) 272-2606 |
| Opfer , Amanda DO | SJMG Emergency Physicians | (406) 723-2585 |
| Ophthalmic Associates of Billings, LLC | Ophthalmic Associates of Billings, LLC | (406) 256-6000 |
| Ordinario , Eric DO | SVHC Yellowstone Urology | (406) 237-5400 |
| Ortiz , Jose MD | Beartooth Billings Clinic | (406) 446-2345 |
| Ortiz, Pedro MD | SVH Montana Heart Institute | (406) 237-5001 |
| Oser, James MD | SJMG Emergency Physicians | (406) 723-2585 |
| Ostahowski, Gary MD | SVHC Hardin Clinic | (406) 665-2205 |
| Ostahowski, Gary MD | SVHC Wound Healing Center | (406) 237-8270 |
| Ostahowski, Gary MD | Big Horn Hospital | (406) 665-2310 |
| Ostahowski, Gary MD | SVH Wound Healing Center | (406) 237-8270 |
| Ostahowski, Gary MD | SVHC OCC Health | (406) 237-8855 |
