- ONERA - The French Aerospace Lab [Palaiseau]
- Observatoire Français des Drogues et des Toxicomanies
- Observatoire Régional de la Santé Nord Pas-de-Calais
- Observatoire des Programmes Communautaires de Développement Rural
- Observatoire régional de la santé
- Occupational Cancer Department
- Occupational Health Department
- Occupational Medicine, Department of Public Health and Clinical Medicine
- Occupational Physiology Laboratory (Vandœuvre-Les -Nancy, France)
- Occupational and Environmental Epidemiology Branch [Bethesda, Maryland]
- Office of Population Research
- Office of Scientific Support for Risk Assessment
- Oncogenetics Laboratory
- Oncogenèse des tumeurs respiratoires et urogénitales
- Oncogénèse et progression tumorale
- Oncologie multidisciplinaire et innovations thérapeutiques
- Ontario Cancer Genetics Network
- Oral medicine and oral surgery department
- Orange Labs [Meylan]
- Oxylipides