Identification of the andrological variables most sensitive to zinc depletion would expedite the diagnosis of male reproductive pathology induced by zinc deficiency. Eleven volunteers living on a metabolic ward were fed a diet composed of a mixture of a semisynthetic formula and conventional foods supplemented with ZnSO4 to supply a total of 1.4, 2.5, 3.4, 4.4, or 10.4 mg Zn/d. After an equilibration period of 28 d (10.4 mg Zn/d), all treatments were presented for 35 d each, the first four in random order and the fifth last. Compared with when they were consuming 10.4 mg Zn/d, volunteers consuming 1.4 mg Zn/d exhibited decreased semen volumes (3.30 vs 2.24 mL) and serum testosterone concentrations (26.9 vs 21.9 nmol/L), and no change in seminal zinc concentrations. Compared with 10.4 mg Zn/d, treatments of 1.4, 2.5, and 3.4 mg Zn/d decreased the total semen zinc loss per ejaculate (6.29 vs 3.81, 4.68, and 5.03 mumols/ejaculate). Seminal loss accounted for 9% of total body zinc loss when 1.4 mg Zn/d was consumed. Seminal phosphorus concentrations were elevated during all four phases of zinc depletion (28.4 vs 32.9, 31.0, 34.2, and 33.6 mmol/L). The findings suggest that serum testosterone concentrations, seminal volume, and total seminal zinc loss per ejaculate are sensitive to short-term zinc depletion in young men.