Recently, less toxic and more effective anaesthetics are essential for marine fishes. Lidocaine belongs to a group of anaesthetics which are used as local anaesthetic in human medicine. This chemical was tested fer winter flounder, Pleunnectes americanus. Anaesthetic effect of lidocaine hydrochloride-sodium bicarbonate mixture (lidocaine $HCl/NaHCO_3$) was tested for the winter flounder at five different temperature regimes: $3^{circ}C,;7^{circ}C,;11^{circ}C,;15^{circ}C;and;19^{circ}C$ Anaesthetic dose and temperature-dependent relationship in exposure and recovery time were observed for the winter flounder of $17.2{pm}0.1cm$ mean total length. Based on the results, anaesthetic lidocaine $HCl/NaHCO_3$ showed rapid exposure time and rapid recovery time for winter flounder. The results indicate that lidocaine $HCl/NaHCO_3$ can be used as suitable anaesthetic for this species.