| CRF | Corticotropin Releasing Factor |
| CRF | Case Report Form |
| CRH | Corticotropin Releasing Hormon |
| CRO | contract research organisation |
| CRP | C-reaktives Protein |
| CRST | Calcinosis (Haut) + Raynaud + Sklerodaktylie + Teleangiektasien (-Syndrom) |
| CS | clinical staging |
| CS | completed stroke |
| CS | Konditionierter Stimulus |
| CsA | Cyclosporin A |
| CSB | Convertin, Stuart-Prower Faktor, Globulin B (-Plasmafraktion) |
| CSD | EKG: Karotissinusdruckversuch |
| CSF | Kolonie stimulierender Faktor |
| c.s.i. | cum signum interogatione |
| CSII | continuous subcutaneous insulin infusion (Insulinpumpe) |
| CSR | Cheyne-Stokes-Respiration |
| CT | Computertomographie |
| CT | cardio-thoracic |
| CTA | cytotoxic antibody |
| CTCL | kutane T-Zell Lymphome |
| CTDF | cytotoxic T-cell differentiation |
| CTF | colorado tick fever |
| CTG | Cardiotokogramm |
| CTL | cytotoxic lymphocyte reaction/ cytotoxische T-Lymphozyten |
| CTP | Cytidintriphosphat |
| CTS | Carpaltunnelsyndrom |
| CTV | colorado tick fever virus |
| CTx | Chemotherapie |
| CU | Colitis ulcerosa |
| CUP | Carcinoma of unknown primary |