- Uehlinger's syndrome (acropachyderma) 757.39
- Uhl's anomaly or disease (hypoplasia of myocardium, right ventricle) 746.84
- Ulcer, ulcerated, ulcerating, ulceration, ulcerative 707.9
- Ulcerosa scarlatina 034.1
- Ulcus - see also Ulcer
- Ulegyria 742.4
- Ulerythema
- Ullrich (-Bonnevie) (-Turner) syndrome 758.6
- Ullrich-Feichtiger syndrome 759.89
- Ulnar - see condition
- Ulorrhagia 523.8
- Ulorrhea 523.8
- Umbilicus, umbilical - see also condition
- Unacceptable
- Unavailability of medical facilities (at) V63.9
- Uncinaria americana infestation 126.1
- Uncinariasis (see also Ancylostomiasis) 126.9
- Unconscious, unconsciousness 780.09
- Under observation - see Observation
- Underdevelopment - see also Undeveloped sexual 259.0
- Underfill, endodontic 526.63
- Undernourishment 269.9