A total of 40 carp were examined. Clove oil anaesthesia had not effect on the haematological profile. The 10-min exposure to clove oil at a concentration of 30 mg/l caused a significant (P < 0.01) increase in the concentration of glucose (GLU) and inorganic phosphate (PHOS) immediately after anaesthesia. Clove oil anaesthesia had not effect on other biochemical indices. Histological examination showed capillary ectasia of gill filaments immediately after clove oil anaesthesia. Twenty-four hours after anaesthesia, no ectasia was observed. No histopathological changes were demonstrated in other tissues following anaesthesia. Results of the examinations suggest that the use of clove oil at a concentration of 30 mg/l does not cause irreversible damage in carp.