- Tracheitis (acute) (catarrhal) (infantile) (membranous) (plastic) (pneumococcal) (septic) (suppurative) (viral) 464.10
- Trachelitis (nonvenereal) (see also Cervicitis) 616.0
- Tracheobronchial - see condition
- Tracheobronchitis (see also Bronchitis) 490
- Tracheobronchomegaly (congenital) 748.3
- Tracheobronchopneumonitis - see Pneumonia, broncho
- Tracheocele (external) (internal) 519.19
- Tracheomalacia 519.19
- Tracheopharyngitis (acute) 465.8
- Tracheostenosis 519.19
- Tracheostomy
- Trachoma, trachomatous 076.9
- Trachyphonia 784.49
- Traction, vitreomacular 379.27
- Train sickness 994.6
- Training
- Trait
- Traits, paranoid 301.0
- Tramp V60.0
- Trance 780.09
- Trans-sexualism 302.50
- Transaminasemia 790.4