Manganese sulphate and nickel sulphate were tested for the induction of gene conversion at the trp5 locus and reverse mutation at the ilv1 locus in D7 strain of Saccharomyces cerevisiae. Nickel sulphate was more toxic than manganese sulphate but did not induce any reverse mutation and gave a weak positive response for conversion. Manganese sulphate was also only slightly mutagenic and convertogenic.