Sodium dichloroacetate (DCA) is a drug with potential for treating patients with stroke and head injury. Conflicting evidence has been published on the mutagenic potential of DCA. A series of genetic tests for mutagenicity and clastogenicity was carried out on pharmaceutical grade DCA. Four types of mutagenicity test were included, with and without metabolic activation where appropriate. These studies included: (i)SalmonellaandEscherichia colimutation (Ames) tests, (ii) thymidine kinase locus forward mutation in L5178Y mouse lymphoma cells, (iii) tests for chromosomal aberrations in Chinese hamster ovary cells, and (iv) anin vivorat bone marrow erythroid micronucleus test. In each study, there was no evidence of mutagenic activity attributable to DCA. It is possible that the present test material, of pharmaceutical grade, has fewer impurities than materials studied in previous reports. These data extend, and in some cases contradict, previous published reports on DCA.