Different levels of dietary S were supplied to sheep receiving high levels of Cu (55 mg/sheep/day) and Mo (34 mg/sheep/day) in their rations. At S intakes of 2,9,4,0 and 5,3 g/sheep/day the hepatic Cu retentions expressed as percentages of total Cu intakes, were 0,24%, 0,11% and -0,04% respectively. An increase in S in the ration from 2,9 to 4,0 g resulted in significant decreases in Mo concentrations of the plasma, spleen, lungs, muscle and testes of the sheep. No further changes in Mo concentration of these organs were observed with a further increase of S from 4,0 to 5,3 g/sheep/day. At the S intakes of 4,0 and 5,3 g/sheep/day, a positive correlation (r = 0,916) was obtained between the Cu and Mo concentrations of the kidney cortex. Such a high correlation may arise because of the depletion of Mo from the kidneys due to the additional S, as observed in the other tissues, while at the same time compounds containing Cu and Mo (unavailable to the body) accumulated in the kidneys.