Objective: This was a pilot study to determine the utility of daily lung ultrasound (LUS) in patients requiring veno-venous extracorporeal membrane oxygenation (VV-ECMO) for acute respiratory distress syndrome (ARDS). Design: This was a prospective, observational study. Setting: The study took place in the intensive care unit at Royal Papworth Hospital in Cambridge, UK. Participants: We recruited adult patients receiving VV-ECMO for ARDS. Interventions: All patients received a lung computed tomography (CT) scan and LUS on admission. Bedside chest radiography (CXR) and LUS were done on a daily basis until patients were decannulated. Measurements and main results: Daily LUS aeration scores were calculated according to the appearance of four defined patterns. An independent radiologist calculated corresponding scores for CT and CXR, retrospectively. These were checked for correlation with LUS aeration scores. There were statistically significant correlations between LUS versus CT ( r = 0.868, p = 0.002) and LUS versus CXR ( r = 0.498, p = 0.018) with good agreement and no evidence of proportional bias. LUS was able to detect 13.5% of pleural effusions and 54.2% of pneumothorax that were not picked up on CXR. In most of the patients who were weaned off VV-ECMO, a progressive reduction of LUS aeration scores corresponding to lung re-aeration was observed. Conclusions: LUS correlated with findings on CT and CXR for quantifying lung aeration and the clinical presentation of patients. LUS also picked up more pleural effusions and pneumothorax than CXR. Together with traditional imaging techniques, the routine use of LUS should be considered for this patient group.