The Bureau of Mines evaluated creep and other properties of extruded zn-30 percent al alloys containing 0 to 0.7 percent mg. The alloys were extruded both above and below the zn-al eutectoid temperature of 275 deg c. Creep behavior is defined for the alloys as extruded and after various heat treatments. Tensile properties, hardness, thermal expansivity, impact resistance, and microstructures are given. The alloys, either with or without magnesium, required substantially less pressure for extrusion near 275 deg c than at higher or lower temperatures. The alloys containing magnesium exhibited significantly greater hardness than the zn-30 percent al alloy. The properties were very sensitive to the processing conditions.