Abstract: A filter for removing substances, including leukocytes and platelets by way of non-limiting example, from whole blood or from blood derivatives, the filter includes a casing containing a layered filter element, at least one layer of this latter being coated with polyurethane; this polyurethane has a number average molecular weight between 10,000 and 20,000 Dalton. A method for forming the layered filter element for a filter such as mentioned above, in which at least one layer of this filter element is impregnated with polyurethane by immersing it in a container of a mixture in which the polyurethane is present. This mixture includes a solution in which the polyurethane is dissolved in a polar solvent such as water.