The spectrophotometric and colorimetric procedures for the assay of serum glutamic-oxaloacetic transaminase (SGOT) activity are assessed. Directions are given for the preparation of reagents and for a procedure that corrects the errors in the spectrophotometric method without altering its basic simplicity. The colorimetric procedure employing dinitrophenylhydrazine showed poor accuracy due, in part, to a large and variable blank. The proposed procedure eliminates the troublesome group of analytic results, "borderline" measurements, a source of diagnostic uncertainty.