The Bureau of Mines conducted research on substitute brazing filler alloys with properties similar to those of silver filler alloys in an effort to conserve silver and reduce hazards from cadmium emissions. Experimental work was conducted first on the commercial silver brazing alloys bag-1, bag-1a, bag-2, and bag-3 to establish criteria for evaluating the substitute alloys. Properties investigated included the wettability of copper, brass, and steel substrates, and the strength of joints made with the filler alloys. A series of experimental alloys containing 50 to 60 pct cu, 20 to 28 pct mn, and 17 to 30 pct zn was prepared and evaluated, together with cu-mn-zn alloys with 5 pct pb or 2 pct ni. Wetting properties and joint strengths were not as good as those for silver filler alloys, and the high application temperatures reduced the copper and brass base metal strengths. However, experimental alloys containing 70 pct cu, 15 to 20 pct mn, and 10 to 16 pct sn had wetting and strength properties approaching those of the silver filler alloys. The cu-mn-sn system has potential for further development as a substitute brazing alloy system, particulary if the melting temperature can be reduced by the addition of other elements without decreasing the ductility and wetting.