In the production of lead batteries two antimony compounds occur: in the casting of grids antimony trioxide (Sb2O3), and in the formation of lead plates stibine (SbH3). Seven workers from the grid-casting area and 14 workers from the formation area were examined with regard to the antimony concentration in blood (Sb-B) and urine (Sb-U). Antimony air concentrations (Sb-A) were measured by means of personal air samplers. Urine samples were collected at the end of the working week, at the beginning (U1) and the end (U2) of the shift, and at the beginning of work following a weekend without Sb exposure (U3). At U2 among the casters, the median Sb-A exposure was 4.5 (1.18-6.6) micrograms Sb/m3 and among the formation workers, 12.4 (0.6-41.5) micrograms Sb/m3. The exposure in both groups is more than 10 times lower than the present threshold limit values. The median Sb-B concentrations in the preshift samples was 2.6 (0.5-3.4) micrograms Sb/l for the casters and 10.1 (0.5-17.9) micrograms Sb/l for the formation workers. The average Sb-U values (U2) were 3.9 (2.8-5.6) micrograms Sb/g creatinine in the casting area and 15.2 (3.5-23.4) micrograms Sb/g creatinine in the forming area. Our investigation indicates that the two antimony compounds show virtually equal pulmonary absorption and renal elimination. The statistically significant correlations between Sb-A/Sb-B and Sb-A/Sb-U form the basis for proposals regarding appropriate biological exposure limits for occupational antimony exposure.