An ion chromatography (IC) method for the determination of copper and zinc in serum and whole blood is described. The sample treatment consists of diluting (2:3 for serum and 1:3 for whole blood) with 50% trichloroacetic acid, centrifuging, and dispensing the liquid directly into the chromatograph. The standard additions technique is used to establish the calibration. The close agreement between IC and spectrophotometric data on copper and zinc in serum and whole blood suggests that ion chromatography may be applied to complex biological matrices with minimal sample preparation.