A method of testing the integrity of a membrane (9c, 11c 32, 33) of at least one filter (9, 11 31) located along a dialysis solution circuit (6 34) the method including, in succession, the steps of:- wetting the test membrane (9c, 11c 32, 33) with an aqueous solution- expelling the aqueous solution from the filter (9, 11 31)- filling a fill chamber (9b, 11a 31b) of the filter (9, 11 31) with a given quantity of gas, after first closing the gas flow lines from the fill chamber (9b, 11a 31b) and- detecting gas flow through the membrane (9c, 11c 32, 33), which bounds the fill chamber (9b, 11a 31b).
