Cancer Organizations: O
- Ospendale S. Andrea EST
- Ospendale S.M. Annunziata-A.S.DI Florence
- Ostalb-Klinikum Aalen
- Osteopathic Medical Oncology and Hematology, PC - Clinton Township
- Osteopathic Medical Oncology and Hematology, PC - Garden City
- Osteopathic Medical Oncology and Hematology, PC - Riverview
- Osteopathic Medical Oncology and Hematology, PC - Woodhaven
- Ostra Sjukhuset
- Ostschweizer Kinderspital
- Oswego Hospital
- Oswego Oncology
- Otaru Ekisaikai Hospital
- Otemae Hospital
- Otemae Hospital
- Otolaryngology Associates
- Otolaryngology Associates at Thomas Jefferson University Hospital
- Otolaryngology Associates of the MidSouth
- Otolaryngology Associates, PC
- Otolaryngology Clinic
- Otolaryngology Head & Neck Surgery Specialists for the Central Coast - San Luis Obispo
- Otolaryngology Head & Neck Surgical Consultants
- Otolaryngology Physicians of Lancaster
- Otolaryngology and Maxillofacial Surgery
- Otolaryngology-Head and Neck Surgery - ENT
- Otolayngology Head & Neck Surgery Specialists for the Central Coast - Arroyo Grande
- Otsego Memorial Hospital
- Otsu Municipal Hospital
- Otsuka America Pharmaceutical, Incorporated
- Otsuka Beijing Research Institute
- Otsuka Pharmaceutical Company, Limited
- Ottawa Health Research Institute
- Ottawa Hospital Regional Cancer Centre - Civic Campus
- Ottawa Hospital Regional Cancer Centre - General Campus
- Ottawa Public Health
- Otto-Meyerhof-Zentrum Tagesklinik
- Oudenrijn Ziekenhuis
- Oulu University Hospital
- Our Lady of Fatima Hospital
- Our Lady of Lourdes Medical Center
- Our Lady of Lourdes Regional Medical Center
- Our Lady of Mercy Medical Center Comprehensive Cancer Center
- Our Lady of the Lake Regional Medical Center
- Our Lady of the Resurrection Medical Center
- Our Lady's Hospice Limited
- Our Lady's Hospital for Sick Children
- Our Lady's Hospital for Sick Children Crumlin
- Outcomes Research Group
- Outcomes Research International
- Outer Banks Hospital
- Ovarian Cancer Study Group
- Ovation Pharmaceuticals
- Overlake Cancer Center at Overlake Hospital Medical Center
- Overland Medical Center
- Overland Park Regional Medical Center
- Overlook Hospital
- Oxford BioMedica
- Oxford Centre for Respiratory Medicine at Churchill Hospital
- Oxford Radcliffe Hospital
- Oxigene, Incorporated
- Oy Eli Lilly Finland AB
- Ozark Cancer Clinic
- Ozarks Medical Center
