Immunodiagnostic tests in which enzymes or antibodies are bound to porous carrier materials can be carried out by employing as porous carrier materials macroporous polymer membranes which are prepared by(a) dispersing an insoluble filler in a solution which contains at least two incompatible polymers in amounts which lead to phase separation in the solution, resulting in a homogeneous casting solution, and(b) applying this solution to a support and carrying out a precipitation coagulation.