Abstract: This invention relates to an in-situ implant that can be produced by placing a sterile, injectable, and water-insoluble complex from a biodegradable polymer and a biocompatible polyether with functional end-groups in the organism, and coagulating them under the influence of the body fluid. This coagulate may optionally contain at least one bioactive substance selected from the group of hormones, immunomodulators, immunosuppressants, antibiotics, cytostatics, diuretics, gastro-intestinal agents, analgesics, local anaesthetics and/or neuropharmacological agents.