SummaryAt high doses and in certain experimental conditions, the cardiotonic glucosides influence the ions movements in several biological systems and especially in the kidney. The mechanism of sodium and water diuresis observed has not been clearly explained yet and gives rise to some difficulties in the interpretation.It has not been definitely demonstrated that, at the usual therapeutic dosages, the cardiotonic glucosides produce diuresis through a mechanism which is distinct from their action on renal haemodynamics. This fact partly results from the incomplete and indirect character of present methods for the investigation of renal circulation.