| C | Zervikalsegment |
| C | Compliance |
| C | Cytosin |
| C1 | Erster Halswirbel |
| Ca | Carcinom |
| CA | Cancer Antigen |
| CA | Chefarzt |
| C.a. | Condylomata acuminata |
| CA125 | Tumormarker |
| CA15-3 | Tumormarker |
| CA19-9 | Tumormarker |
| CA72-4 | Tumormarker |
| CABG | coronary artery bypass graft |
| CAD | Coronary artery disease |
| CAF | Zytostase mit Cyclophosphamide,Adriamycin und 5-FU |
| CAH | chronisch aggressive/aktive Hepatitis |
| CAH | Carbonatanhydrase |
| CAH | kongenitale adrenale Hyperplasie |
| CAI | clincal activity index (=CDAI bei MC) |
| CALL | common ALL |
| CALLA | CALL-Antigen |
| CAM | Chorion Allantois Membran |
| cAMP | zyklisches Adenosinmonophosphat |
| CAP | katabolisches Aktivierungsprotein |
| CAP | Coronary Artery Perfusion |
| CAP | Community-Aquired Pneumonia |
| CAP | chronisch apikale Parodontitis |
| CAPD | kontinuierliche ambulante Peritonealdialyse |
| CARD15 | Caspase Recruitment Domain |
| CAV | croup associated virus |