The anaesthesia induced by cyclohexylamine derivatives in cats was studied by comparing the effects induced by four pairs of agents: acepromazine/ketamine, xylazine/ketamine, zolazepam/tiletamine and medetomidine/ketamine. Acepromazine/ketamine was free of undesirable side effects but provided inadequate anaesthetic cover. The other combinations differed only in the dosage, the quality of the anaesthesia and the importance of the side effects. Medetomidine/ketamine was the best combination; it induced a good degree of anaesthesia with small doses and was free of major side effects.