Cell-free lysates of the strict anaerobe Oxalobacter formigenes contained the following enzymatic activities: oxalyl coenzyme A reductase, glyoxylate carboligase, tartronic semialdehyde reductase, and glycerate kinase. NAD(P)-linked formate dehydrogenase, serine-glyoxylate aminotransferase, and NAD(P) transhydrogenase activities were not detected. These results support the hypothesis that O. formigenes assimilates carbon from oxalate by using the glycerate pathway, whereby oxalate is reduced to 3-phosphoglycerate before entering common biosynthetic pathways.