The invention relates to biopolymer-gel based depot systems for prolonged and/or controlled release delivery of biologically active agents, methods for the manufacture of the biopolymer based gel-depots which include a biologically active agent, and uses of such biopolymer gel-depots in therapy. The biopolymer-gel based depot systems comprise a biocompatible polyaminosaccharide and/or protein; a biocompatible phosphate and/or sulphonamide compound; a biologically active agent; an aqueous insoluble alkaline earth metal phosphate; and a biocompatible glycan and/or proteoglycan.