Serum and aqueous humour zinc and copper concentrations of 44 patients with glaucoma and cataract were determined. Serum values were found within normal ranges. The highest mean copper concentration was seen in the glaucoma group. In addition there was a significant negative correlation between the aqueous humour levels of zinc and copper in patients with glaucoma. It was concluded that an increased copper value together with a low zinc value might be of importance in patients with glaucoma.