BACKGROUND Pneumoperitoneum and steep Trendelenburg position promote the formation of pulmonary atelectasis during laparoscopic gynaecological surgery. OBJECTIVE To determine whether lung ultrasound-guided alveolar recruitment manoeuvres could reduce peri-operative atelectasis compared with conventional recruitment manoeuvres during laparoscopic gynaecological surgery. METHODS Randomised controlled trial. METHODS Tertiary hospital, Republic of Korea, from August 2018 to January 2019. METHODS Adult patients scheduled for laparoscopic gynaecological surgery under general anaesthesia. METHODS Forty patients were randomised to receive either ultrasound-guided recruitment manoeuvres (manual inflation until no visibly collapsed area was seen with lung ultrasonography; intervention group) or conventional recruitment manoeuvres (single manual inflation with 30 cmH2O pressure; control group). Recruitment manoeuvres were performed 5 min after induction and at the end of surgery in both groups. All patients received volume-controlled ventilation with a tidal volume of 8 ml kg-1 and a positive end-expiratory pressure of 5 cmH2O. METHODS The primary outcome was the lung ultrasound score at the end of surgery; a higher score indicates worse lung aeration. RESULTS Lung ultrasound scores at the end of surgery were significantly lower in the intervention group compared with control group (median [IQR], 7.5 [6.5 to 8.5] versus 9.5 [8.5 to 13.5]; difference, -2 [95% CI, -4.5 to -1]; P = 0.008). The intergroup difference persisted in the postanaesthesia care unit (7 [5 to 8.8] versus 10 [7.3 to 12.8]; difference, -3 [95% CI, -5.5 to -1.5]; P = 0.005). The incidence of atelectasis was lower in the intervention group compared with control group at the end of surgery (35 versus 80%; P = 0.010) but was comparable in the postanaesthesia care unit (40 versus 55%; P = 0.527). CONCLUSIONS The use of ultrasound-guided recruitment manoeuvres improves peri-operative lung aeration; these effects may persist in the postanaesthesia care unit. However, the long-term effects of ultrasound-guided recruitment manoeuvres on clinical outcomes should be the subject of future trials. BACKGROUND ClinicalTrials.gov (NCT03607240).