[en] We have compared severely obese patients (body mass index > 35 kg m-2) undergoing laparoscopic or open gastroplasty (n = 15 in each group) to determine if laparoscopy results in any benefit in the obese. Postoperative pain, measured on a 100-mm visual analogue scale, and opioid consumption were recorded during the first two days after operation. Tests of pulmonary function were performed and SpO2 was measured 4 h after surgery and on days 1, 2 and 3 after operation. Pain at rest was similar in the two groups, but in the laparoscopy group, requirements for postoperative opioid were 50% less (P < 0.05). Pain intensity during mobilization and on coughing was significantly less after laparoscopy (differences between mean pain scores in both groups ranged from 20 to 32 mm during mobilization and from 32 to 34 mm during coughing). Forced vital capacity, forced expiratory volume in 1 s and peak expiratory flow rate were reduced significantly less after laparoscopic gastroplasty than after open gastroplasty (on day 1 forced vital capacity was reduced by 50% compared with 64%, forced expiratory volume in 1 s was reduced by 50% compared with 66% and peak expiratory flow rate by 45% compared with 60%). SpO2 values were significantly greater in the laparoscopy group (day 1: mean 95 (SD 2)% vs 91 (5)%; day 3: 97 (1)% vs 94 (3)%). This study suggests that the beneficial effects observed after laparoscopic gastroplasty in morbidly obese patients were similar to those reported after laparoscopic cholecystectomy in non-obese patients.