After laparoscopic surgical procedures, residual gas in the abdominal cavity can cause post-operative pain, which is commonly located in the shoulder region. Previous studies suggested that post-laparoscopy pain can be prevented by active suctioning of intraabdominal gas at the end of surgery.This randomized controlled trial (registered at DRKS 00,023,286) compared active suctioning versus manual compression in their ability to reduce pain after laparoscopic cholecystectomy. Patients scheduled for laparoscopic cholecystectomy were eligible for trial participation. The primary outcome measure was post-operative pain intensity after 12 h. All the patients were examined by MRI scanning to quantify the intraabdominal gas volume after the intervention.As planned, 60 patients were recruited. The two groups (n = 30 each) were very similar at the end of surgery. Active suctioning reduced the amount of residual pneumoperitoneum more than simple compression (median volume 1.5 versus 3.0 ml, p = 0.002). The primary outcome measure, abdominal pain after 12 h, was slightly lower in the intervention group (- 0.5 points, 95% confidence interval + 0.5 to - 1.7), but without reaching statistical significance (p = 0.37). After 12 h, shoulder pain was present in 10 patients in each group (p = 1.0). Independent of group assignment, however, residual gas volume was significantly associated with higher pain intensity.Active suctioning appears to have only a minor preventive effect on post-laparoscopy pain, probably because evacuation of the pneumoperitoneum remains incomplete in some patients. Other more effective maneuvers for gas removal should be preferred.