BACKGROUND: Serious pulmonary complications after lung surgery increase morbidity and mortality in perioperative period. Ketamine hydrochloride produces strong analgesic effect in spite of the psychomimetic effects. Intravenous anesthesia with ketamine was performed in lung surgery of patients with decreased pulmonary function and compared with inhalation anesthesia with enflurane. METHODS: Sixty patients, scheduled for elective lung surgery, were randomly assigned to two groups. Patients received either enflurane (Group 1, n=30) or ketamine (Group 2, n=30) as main anesthetic drug. Blood pressure and heart rate were compared in preinduction, postinduction, postintubation, postincision, intraoperative period (30 minutes, 60 minutes) and recovery room between groups, and in each group. Arterial blood gas analysis was compared in preoperative period, intraoperative period and recovery room between groups. Postoperative psychological complications evaluated in group 2. RESULTS: Blood pressure and heart rate were significantly different in postinduction, postintubation and recovery room between groups. PaO2 in group 2 was higher than in group 1 during intraoperative period and recovery room. Postoperative psychological complications occured in 4 patients (13%) in group 2. CONCLUSIONS: Ketamine affords advantage over enflurane anesthesia in terms of PaO2 during intraoperative period and recovery room in lung surgery of patients with decreased pulmonary function.