Abstract: A method is provided for repairing a cement sheath around the casing in a well bore in which a retainer is inserted within the casing below perforations in the casing adjacent an area of cement sheath requiring repair; a packer means is inserted within the casing above perforations in the casing adjacent the area of cement sheath requiring repair; a gellable polymer composition is injected through the perforations and into the well bore and adjacent underground formation and allowed to gel; thereafter a sufficient amount of cementitious material is injected through the perforations into the well bore around the casing with sufficient pressure applied to squeeze gel from the well bore into the formation and replace the gel with cementitious material; the cementitious material is allowed to set; and the packer, cementitious material and retainer are removed from the casing interior.