| AAAI | American Academy of Allergy and Immunology |
|---|---|
| AAALAC | American Association for Accreditation of Laboratory Animal Care |
| AAAS | American Association for the Advancement of Science |
| AAB | American Association of Bioanalysts; aminoazobenzene |
| AABB | American Association of Blood Banks |
| AABCC | alertness (consciousness), airway, breathing, circulation, cervical spine |
| AABS | automobile accident, broadside |
| AAC | antibiotic-associated [pseudomembranous] colitis; antimicrobial agent-induced colitis; augmentative and alternative communication |
| AACA | acylaminocephalosporanic acid |
| AACC | American Association for Clinical Chemistry |