This study was designed to investigate the possible participation of urethane, pentobarbital sodium and thiopental sodium anaesthesia in the lung oedema induced by alpha-naphthylthiourea (ANTU), which is a well known noxious chemical agent in the lung. ANTU when injected intraperitoneally (i.p.) into rats (10 mg kg(-1) i.p.) produced lung oedema as indicated by an increase in lung weight/body weight (LW/BW) ratio and pleural effusion (PE) reaching a maximum within 4 h. Administration of urethane prior to ANTU, at doses of 100 and 200 mg (100 g)(-1), elicited a significant and dose-dependent inhibition in LW/BW ratio and PE. Thiopental sodium at doses of 25, 50 mg kg(-1), also produced a significant and dose-dependent inhibition of both parameters. Prior i.p. injection of pentobarbital sodium at a dose of 40 mg kg(-1) elicited a significant inhibition in both parameters. These results suggest that i.p. urethane, thiopental sodium and pentobarbital sodium pretreatment have a prophylactic effect on ANTU-induced lung injury in rats. The possible role of the anaesthetics in lung oedema induced by ANTU and the possible underlying mechanisms are discussed. (C) 2002 Elsevier Science Ltd.