Abstract: The present invention relates to an impermeable flexible multicompartment bag for medical use for sterile solutions, and to a method for the preparation of such bags. Impermeable flexible multicompartment bags for medical use for sterile solutions for perfusions, consisting of two welded sheets of a composite material wherein the sheets forming the inner wall of the bag consist of a polypropylene and are bonded to an outer layer of a thermoplastic polymer by means of a polyolefin layer, characterized in that the sheets facing the contents of the bags which are made of a homophase copolymer of propylene are immediately welded in the intercompartment region and in the peripheral region such that the weld forming the intercompartment region can be ruptured with a force in the range of from 10 to 30 N while the weld in the peripheral region cannot be ruptured.