Magnetoresistances of alloys of Mn in Cu (5.4 atomic per cent Mn), Mn in Zn (0.12 atomic per cent Mn) and Cr in Zn (0.10 atomic per cent Cr) are measured in the magnetic field up to about 76 KOe at liquid helium temperature. The magnetoresistance of CuMn alloy decreases with increasing field and shows a reproducible hysteresis. The ratio of the decrease of resistance for the strongest magnetic field applied here to the field-free resistance at 0°K is about 7 per cent, while the ratio of the decrease of resistance for an infinite magnetic filed at 4.24°K to the field-free value at 0°K is estimated to be 38 per cent, using our experimental results and the method proposed by K. Yosida. Magnetoresistances of ZnMn and ZnCr alloys are also measured under the same experimental conditions as that for CuMn alloy
