A relatively simple and reproducible procedure involving copper-chelate affinity chromatography for the isolation of copper-zinc-superoxide dismutase (E.C. 1.15.1.1) and catalase (E.C. 1.11.1.6) from human erythrocytes has been developed. Using this method, the two enzymes were easily and highly purified and appeared to be homogeneous as judged by polyacrylamide gel electrophoresis.