Continuous positive airway pressure ventilation (CPAP) tends to reduce the risk of post-operative pulmonary infection by recruiting poorly ventilated areas. In human renal transplantation, pulmonary infection is a major problem with a high mortality rate in these immuno-depressed patients. The risk is further increased by the need for recipient maximal hydration during surgery to ensure satisfactory graft function. We therefore thought that it would be appropriate to use CPAP preventively during the immediate post-operative period. In a series of 60 successive patients who benefited from CPAP, the incidence of pulmonary infections was only 5%, which compared favourably with a 14.3% incidence in a previous series of 77 patients without preventive CPAP. Moreover, the 3 pulmonary infections that occurred were rapidly cured and the transplanted kidney could be saved in 2 cases; one patient required dialysis. No death was recorded.