In this study. the effects of an anaesthetic quinaldine sulphate (QS) and a muscle relaxant, diazepam (D). on sea bass (Dicentrarchus labrax) juveniles (8-9 g) were investigated. When used together with D, the anaesthetic effect of QS was significantly increased. The fish entered light anaesthesia at 15 ppm QS, as compared to S ppm QS + 1 ppm diazepam (D). Similarly, a deep anaesthesia level was reached at only 7.5 ppm QS + 1 ppm D as compared to 20 ppm of QS. The use of QS alone at high concentrations (7.5-25 ppm) increased mortality from 10% to 100%. No post-exposure mortality occurred in any of the fish treated with QS plus D at all anaesthesia levels. Depending on the anaesthetic concentrations used. the time to loss of equilibrium and recovery time were 1-3 and 2-6 min, respectively. The combination of QS and diazepam significantly decreased the excitement and hyperactivity of the fish in confined space without leading to mortality. it appears that the suitable light and deep sedation stages of anaesthesia for transportation and handling of the sea bass juveniles (8-9 g) were obtained with dosages of S ppm QS + 2 ppm D and 7-10 ppm QS plus 2 ppm D, respectively.