Zinc stable isotopes can be applied to the identification of populations at risk for zinc deficiency and to monitoring the effects of zinc intervention studies designed to improve zinc nutriture. Techniques using these isotopes can provide information on how effectively the intestine is absorbing exogenous dietary zinc and conserving endogenous zinc. They can also yield estimates of the quantity of readily exchangeable zinc in the body. Data derived from stable-isotope studies can provide extensive information on zinc status and the bioavailability of dietary zinc, allowing researchers to relate zinc intake to physiologic and pathologic conditions. Application of these techniques in longitudinal studies can provide quantitative data on the effectiveness of prevention programs such as simple community measures aimed at reducing dietary phytate and zinc fortification and supplementation programs. Further, judicious application of zinc stable-isotope techniques could make an important contribution to progress toward the eradication of zinc deficiency in infants and young children in the developing world.