Sprague-Dawley and Brown-Norway female rats were chronically exposed to cadmium. The metal was administered either in drinking water at a concentration of 20 or 100 ppm for 13 months or intraperitoneally (i.p.) at the dose of 1 mg/kg, 5 times a week for 4 months. Anti-laminin and anti-type IV procollagen antibodies (laminin and type IV procollagen are components of the glomerular basement membranes) were sequentially assessed by radioimmunoassay in serial serum samples. Anti-type IV procollagen antibodies were never detectable whereas anti-laminin antibodies were transiently found in the serum of Sprague-Dawley rats only. In the i.p. group, the antibodies were detected between week 4 and 8, whereas in the oral treatment group, they were detected between month 6 and 8. At the same time, the concentration of cadmium in kidney cortex averaged about 100 ppm in the 20 ppm cadmium group and about 200 ppm in the 2 other treatment groups. The pathogenic significance of these antibodies in chronic cadmium intoxication of Sprague-Dawley rats remains to be assessed since their occurrence was not associated with concomitant immunoglobulin deposits in the kidneys.