T&A (tonsillectomy and adenoidectomy)

T&C (type and cross)

T&H (type and hold)

T&S (type and screen)

T&X (type and crossmatch)

T3 (triiodothyronine)

T4 (thyroxine)

Ta (tantalum [element])

TA (transactional analysis)

TA (toxin-antitoxin)