In the present study clove oil extract as an anaesthetic in juvenile Persian sturgeon (Acipenser persicus) has been studied. To this end, 150 juvenile Persian sturgeons with average weight of 76.55 ± 2.15 gwere divided into15 fiberglass tanks. Then three treatment groups, one negative control group and one positive control group, each with three replicates, were considered. The fish of control groups were exposed to 50, 100 and 150 mg/l of clove oil extract as anaesthetic, respectively. Results indicated no statistical difference in stages of anaesthesia for different clove oil extract concentrations. Anaesthesia and recovery times were calculated as less than 3 minutes for all drug concentrations. According to histological examination, no pathologic sign was detected in kidney, liver and gill tissues of the sampled fishin the anaesthesia test in different concentrations. In long time exposure (20 minutes) to 150 mg/l clove oil extract oedema and epithelium lifting in secondary lamella of gill was recorded but no pathological sign was observed in kidney and liver tissues. Due to the results of the present study, the 50 mg/l clove oil extract is recommended as a standard anaesthesia for juvenile Caspian sturgeon. Also, elevation of this drug dose to 150 mg/l is acceptable and has no histopathologic effects in this fish.