SummaryWe report our experience using negative pressure ventilation (NPV) to support 40 infants who required prolonged positive pressure ventilation after cardiac surgery (average duration of post‐operative positive pressure ventilation was 9.2 days). NPV was used for an average of 2.4 days, during which 20 patients were weaned to spontaneous unsupported ventilation, and 20 patients required reintubation. Progressive tachypnoea during NPV was a reliable sign of respiratory insufficiency and preceded failure of NPV.Patients who failed one trial of NPV were likely to fail later trials (11 of 13 failed repeated attempts at NPV). Complications following this therapy were minor.NPV may be successfully used as an alternative form of respiratory support for some infants who require prolonged positive pressure ventilation after cardiac surger