- Transposition (congenital) - see also Malposition, congenital
- Transverse - see also condition
- Transvestism, transvestitism (transvestic fetishism) 302.3
- Trapped placenta (with hemorrhage) 666.0
- Trauma, traumatism (see also Injury, by site) 959.9
- Traumatic - see condition
- Treacher Collins' syndrome (incomplete facial dysostosis) 756.0
- Treitz's hernia - see Hernia, Treitz's
- Trematode infestation NEC 121.9
- Trematodiasis NEC 121.9
- Trembles 988.8
- Trembling paralysis (see also Parkinsonism) 332.0
- Tremor 781.0
- Trench
- Treponema pallidum infection (see also Syphilis) 097.9
- Treponematosis 102.9
- Triad
- Trichiasis 704.2
- Trichinella spiralis (infection) (infestation) 124
- Trichinelliasis 124
- Trichinellosis 124
- Trichiniasis 124
