The mortality experience of 1345 male workers in a lead and zinc smelting plant was followed from 1973 to 1991. Information on the erythrocyte glucose-6-phosphate dehydrogenase (G6PD) phenotype was available for 1,222 (90.9%) cohort members, which provided the opportunity to compare the mortality experience of G6PD-deficient subjects to wild-type-G6PD coworkers with similar exposure to lead. A significant decrease in mortality was observed among the total cohort as well as among the subcohort of production and maintenance workers. Most deaths (27 of 31) and all cancer deaths occurred among production and maintenance workers. Lung cancer mortality was lower than expected. Two deaths from stomach cancer were observed versus 0.6 expected. Mortality from all causes and cancer mortality were lower among production and maintenance workers with the G6PD-deficient phenotype compared to coworkers with the wild-type phenotype. Although the low statistical power of this study prevents conclusive inference, lead smelter workers with the G6PD-deficient phenotype did not suffer adverse health outcomes in terms of mortality from all causes and cancer mortality compared to coworkers with the wild-type G6PD.