- Atelomyelia 742.59
- Athelia 757.6
- Atheroembolism
- Atheroma, atheromatous (see also Arteriosclerosis) 440.9
- Atheromatosis - see also Arteriosclerosis
- Atherosclerosis - see Arteriosclerosis
- Athetosis (acquired) 781.0
- Athlete's
- Athletic team examination V70.3
- Athrepsia 261
- Athyrea (acquired) (see also Hypothyroidism) 244.9
- Athyreosis (congenital) 243
- Athyroidism (acquired) (see also Hypothyroidism) 244.9
- Atmospheric pyrexia 992.0
- Atonia, atony, atonic
- Atopy NEC V15.09
- Atransferrinemia, congenital 273.8
- Atresia, atretic (congenital) 759.89
- Atrichia, atrichosis 704.00
- Atrioventricularis commune 745.69
- Atrophia - see also Atrophy
- Atrophoderma, atrophodermia 701.9
