In cell free extract from Neisseria meningitidis an enzyme has been found which catalyses the oxidation of L-malate to oxaloacetate in the absence of pyridine nucleotides, using ferricyanide as electron acceptor. The enzyme was found to be particle-bound, as determined by sucrose gradient centrifugation. Activity corresponding to this enzyme was demonstrated in extracts from all strains tested of selected Neisseria species. In contrast to the large differences in NAD-linked malate dehydrogenase activity among the species, the interspecies variation of the pyridine nucleotide independent oxidation of malate was not sufficiently distinct to be useful for classification purposes.