The mechanism underlying the reduced Cu status in rats fed on a high-sulphide diet was investigated. Male rats aged 6 weeks were fed ad libitum on purified diets containing either 0 or 500 mg S2-/kg and demineralized water for a period of 2 weeks. The high-sulphide diet had no effect on feed intake, body-weight gain or weight of liver and kidney but significantly reduced Cu concentrations in plasma and kidney. Biliary Cu excretion was decreased significantly in rats fed on the high-sulphide diet. Apparent Cu absorption (Cu intake-faecal Cu) and true Cu absorption (Cu intake-(faecal Cu-biliary Cu)) were significantly lowered after sulphide feeding for 2 weeks. Rats fed on the high-sulphide diet excreted less Cu in urine than did the controls. We conclude that high sulphide intake reduces Cu status in rats through inhibition of Cu absorption which is reflected by a decrease in biliary Cu excretion as a secondary feature.