Objectives: To describe current nutrition delivery practices and to identify barriers to nutrition in patients receiving venovenous or venoarterial extracorporeal membrane oxygenation (ECMO) in multiple centres in Australia and New Zealand. Design, setting and participants: A prospective, multicentre, observational study, set in eight intensive care units in Australia and New Zealand, of adults treated with ECMO who were expected to receive enteral nutrition (EN) or parenteral nutrition (PN) therapy for > 72 hours. Data were collected from the start of ECMO until 7 days after ECMO cessation. Results: There were 107 patients enrolled, with a median age of 42 years (interquartile range [IQR], 31–56 years), and 54 patients (50%) were men. EN was the most commonly delivered mode of nutrition (on 84% of days) although it was interrupted on 53% of days. The median interruption duration was 8 hours (IQR, 4–5 hours] per episode. The two most common barriers to EN delivery were fasting for a therapeutic or diagnostic procedure and high gastric residual volumes. Median daily calorie and protein deliveries from EN and/or PN were 1680 kcal (IQR, 960–2100 kcal) and 72 g (IQR, 42–98 g) of protein. For patients who received EN and/or PN, median calorie and protein deficits during the study period were -7118 kcal (IQR, -11 614 to -4510 kcal) and -325 g (IQR, -525 to -188 g) of protein. Conclusions: EN was the most commonly used nutritiondelivery mode during ECMO treatment but was frequently interrupted. Compared with estimated calorie and protein requirements, lesser but reasonably acceptable amounts were delivered, although calorie and protein deficits still existed.