The invention relates to device for mixing two pasty materials, especially a dental impression material with a catalyst material. Said device is fitted with a housing (42) having a substantially cylindrical section (44) with two radial inlets (68, 70) for both pasty materials on the back end of said section and an outlet (52) for the mixed pasty materials on the front end of the cylindrical section (44). The inventive device also includes a driveable mixing shaft (38) extending through the cylindrical section (44) and rotationally mounted in the housing (42). The mixing shaft (38) has a plurality of rigid mixing elements (74) spaced from an axis (72) for mixing both pasty materials as they pass through the cylindrical section (44) of the housing (42). The mixing shaft (38) has at least one deflecting element (80) in the area of the inlets (68, 70) for supporting transport in axial direction of the pasty material entering the cylindrical section (44) of the housing (42) through the inlets (68, 70), wherein the at least one deflecting element (80) has a deflecting surface (82) extending around the axis (72) and which is inclined in relation to the radial plane of said axis (72).