Thirty-two pigs, weaned at 28 days of age with an average body weight of 9 kg, were used in an experiment devoted to the assessment of the bioavailability of an organic Zn source (ZnOrg) compared to Zn sulfate. Pigs were fed a basal diet containing 28 mg'kg-11 of Zn supplemented with ZnS04 or ZnOrg to provide 0,10,20 and 30 mg'kg-1 of supplemental Zn. In order to reduce the amount and the variability of their Zn stores, pigs were fed the basal diet for a 7-day adjustment period preceding a 19-day experimental period. Growth performance and bone bending moment were not affected by the level nor the source of zinc. On the contrary, plasma zinc concentration and alkaline phosphatase activity (P < 0.001), bone zinc concentration (P < 0. 001), liver and empty body zinc concentrations (P < 0.01) as well as the amount of Zn retained estimated both by the balance technique (BT) (P < 0.001) and by the comparative slaughter technique (CST) (P < 0.01) increased linearly in response to supplemental Zn. However, the two Zn sources exhibited a similar bioavailability. Twenty-seven percent of Zn intake was retained when measured by means of the balance technique, regardless of the dietary level or zinc source. Zn retention was 54% lower when measured by means of the CST as compared to the BT.