OBJECTIVES The optimal level of suction on digital chest drainage devices after lobectomy using video-assisted thoracoscopic surgery (VATS) is unknown and varies between thoracic centres. In this randomized controlled trial, we assessed the potential benefits of low suction of-2 cmH 2 O compared to-10 cmH 2 O, using a digital drainage device. METHODS Two hundred and twenty-eight patients were randomized into 2 groups after VATS lobectomy for suspected or confirmed lung cancer. Primary outcome was time to chest drain removal. Drain data were obtained from the digital drainage devices, and patient data were obtained from medical records during admission, with a follow-up until postoperative day 30. RESULTS For the-2 cmH 2 O and-10 cmH 2 O groups, median (interquartile range) drainage duration was 27.4 h (23.3-71.2) and 47.5 h (24.5-117.8) (P = 0.047), and the incidence of prolonged air leak >5 days was 14.4% and 24.3% (P = 0.089), respectively. Median total fluid production was 566 h (329-1155) ml and 795 h (454-1605) ml (P = 0.007). Median time to consistent air leak cessation (<20 ml/min) was 5.2 h (0.3-34.2) and 23.7 h (0.8-90.8) (P < 0.001). There were no differences in the proportion or the size of the pneumothorax or subcutaneous emphysema after drain removal, and no differences were observed in postoperative morbidity. Median length of in-hospital stay was 2.0 days (2.0-5.8) and 3.0 days (2.0-9.0) (P = 0.18). CONCLUSIONS A low suction level significantly shortened drainage duration, time to air leak cessation and total fluid production, without increasing morbidity. Clinical trial registration number NCT02911259.