Endurance training effects on zinc status were assessed by comparing 13 highly trained (HT) and 10 untrained (UT) women. Blood and 24-h urine samples before and after a 25-mg oral Zn load, and 3-d dietary records were evaluated. Mean daily Zn intakes did not differ and were below the Recommended Dietary Allowances for both groups. Fasting concentrations of plasma Zn, serum albumin, alpha 2-macroglobulin, and erythrocyte Zn content did not differ. However, HT women had significantly (p less than 0.05) higher urinary Zn excretion (HT: 6.7 +/- 0.8 and UT: 4.5 +/- 0.7 mumol/d) and reduced responses to the oral Zn than did UT in terms of maximal responses (HT: 11.0 +/- 1.6 and UT: 16.2 +/- 1.2 mumol/L) and areas under the curve (HT: 34.8 +/- 2.7 and UT: 43.6 +/- 2.7 mumol.L-1.4h-1). The greater urinary Zn excretion by HT women may reflect higher rates of skeletal muscle turnover. Whether their reduced responses to the Zn load reflect differences in plasma volume, entry or removal of plasma Zn, or absorption is unknown.