| AChRA | Acetylcholin-Rezeptor-Antikörper |
| ACI | A. carotis interna |
| ACLA | Anti-Cardiolipin-Antikörper |
| ACLS | Advanced Cardiac Life Support |
| ACMP | American College of Medical Physics |
| ACO | Zytostase mit Adriamycin, Cyclophosphamid und Vincristin (Oncovin) |
| AcO | Acetato |
| acP | saure Phosphatase |
| ACP | Acyl-Carrier-Protein |
| ACPA | Anti-cytoplasmatische-Antikörper |
| ACR | anti constipation regimen |
| ACR | American College of Radiology |
| ACR | American College of Rheumatology |
| ACS | Akutes Koronarsyndrom |
| ACS | American Cancer Society |
| ACT | activated coagulation time |
| ACTH | adrenocorticotrophes Hormon |
| ACV | Acyclovir |
| ACVB | Aorto-Coronarer-Venen-Bypass |
| Acyl | CO.-Gruppe |
| ad | Rezept: in, bis, auf, zu |
| AD | accessory anterior descending (coronary artery) |
| ad. | addiere |
| ad | autosomal dominant |
| AD | Alzheimer Demenz |
| ADA | Adenosindeaminase |
| ADA | American Dental Association |
| ADC | Adenylatcyclase |
| ADC | Augen-Diagnostik-Center |
| ADCC | antibody dependent cell-mediated cytotoxicity |