- Tenesmus 787.99
- Tenia - see Taenia
- Teniasis - see Taeniasis
- Tennis elbow 726.32
- Tenonitis - see also Tenosynovitis
- Tenontosynovitis - see Tenosynovitis
- Tenontothecitis - see Tenosynovitis
- Tenophyte 727.9
- Tenosynovitis 727.00
- Tenovaginitis - see Tenosynovitis
- Tension
- Tentorium - see condition
- Teratencephalus 759.89
- Teratism 759.7
- Teratoblastoma (malignant) (M9080/3) - see Neoplasm, by site, malignant
- Teratocarcinoma (M9081/3) - see also Neoplasm, by site, malignant
- Teratoma (solid) (M9080/1) - see also Neoplasm, by site, uncertain behavior
- Terminal care V66.7
- Termination
- Ternidens diminutus infestation 127.7
- Terrors, night (child) 307.46
- Terry's syndrome 362.21