Eponyms beginning with O
- Opitz-Kaveggia syndrome
- Opitz-Trigozephalie-Syndrom (German)
- Opitz’ syndrome
- Oppenheim's disease
- Oppenheim's gait
- Oppenheim's reflex
- Oppenheim's sign
- Oppenheim's symptom
- Oppenheim's syndrome
- Oppenheim's vazeline
- Oppenheim-Turner syndrome
- Oppenheim-Urbach disease
- Oppenheim-Urbach syndrome
- Oppenheim’s foot reflex
- Oppler’s bacillus
- Orbeli's effect
- Orbeli's phenomenon
- Orbeli's syndrome (Dimitrij J. Orbeli)
- Orbeli-Ginetsinski phenomenon (Leonid Abgarovich Orbeli)
- Ormond’s disease
- Ormond’s syndrome
- Orsi-Grocco method
- Orthmann's tumour
- Ortner's syndrome 1
- Ortner's syndrome 2