Twenty-two welders working with high chromium alloyed electrodes have been examined. Biological monitoring of exposure was accompanied by measurement of the hydrosoluble fraction of chromium in the air. Several indices of early renal tubular damage were also determined. The close relationship between airborne and urinary chromium suggests that the urinary excretion of the metal at the end of exposure, and particularly its increase above baseline values, are reliable indicators of absorption rate. The measurement of the renal clearance of diffusible chromium-taken as an index of body burden-showed the influence of the lower exchange rate compartment on the relationship between environmental and urinary chromium. Although the degree of exposure was the same, the urinary excretion of chromium was higher in the workers with a greater chromium body burden. The evaluation of some early nephrotoxicity indicators yielded no dose-effect relationship, even if a more frequent pathological response" was observed in the subjects with a higher degree of exposure to chromium. © 1979 Springer-Verlag."