cis-Diamminedichloroplatinum (II), an antitumor compound which exhibits mutagenic activity, and its degradation products platin B salt, magnus red, and magnus red anion salt were tested in the Ames microbial mutagenicity assay. The purpose of this investigation was to determine if the positive mutagenic response of the platinum compound could be due to, or enhanced by, the presence of degradation products. Results indicate that platinum degradation complexes are weak mutagens which are capable of inducing both base pair and frameshift-type mutations.