- Observation Medicine, An Issue of Emergency Medicine Clinics of North America
- Obstetric and Gynecologic Emergencies, An Issue of Emergency Medicine Clinics of North America
- Occupational Emergency Medicine
- Of the Epidemics - and Historic Epidemics
- On Call Radiology
- Oncologic Emergencies
- Oncologic Emergency Medicine
- Operational and Medical Management of Explosive and Blast Incidents
- Operative Techniques and Recent Advances in Acute Care and Emergency Surgery
- Organ Failure, A Simple Guide To The Condition, Diagnosis, Treatment And Related Conditions
- Orthogeriatrics
- Orthopedic Emergencies
- Orthopedic Emergencies, An Issue of Emergency Medicine Clinics of North America
- Orthopedic Urgencies and Emergencies, An Issue of Orthopedic Clinics
- Orthopedic Emergencies, An Issue of Emergency Medicine Clinics of North America
- Orthopedic Urgencies and Emergencies, An Issue of Orthopedic Clinics
- Orthostatic Hypotension in Older Adults
- OSCE Revision for the Final FRCEM
- Otitis: The Expert's Diagnostic Guide
- Oxford American Handbook of Emergency Medicine