Calcium and phosphorus have been shown to inhibit the availability of zinc for absorption in animal studies, but limited information is available on this subject in man. In the present study, the effect of both calcium and phosphorus on zinc metabolism was investigated in adult men by determining metabolic balances of zinc during three intake levels of calcium of 200, 800, and 2000 mg/day, and during two intake levels of phosphorus of 800 and 2000 mg/day. The analyzed dietary zinc intake was normal and was kept constant throughout all study phases. Increasing the calcium intake from 200 mg to two higher intake levels up to 2000 mg/day did not significantly change the urinary or fecal zinc excretions or the zinc balance. Also, increasing the phosphorus intake from 800 to a high intake of 2000 mg/day did not have any effect. The simultaneous use of the high calcium and high phosphorus intake also had no effect on zinc excretions and on the zinc balance.