Experiments were performed to investigate the effects of polychlorinated biphenyl (PCB) on calcium metabolism, femur morphometry, and nephrotoxicity. Fischer 344 rats were dosed daily IG for 5, 10, or 15 weeks with 0, 0.1, 1, 10 or 25 mg PCB/kg body weight. After 5, 10 and 15 weeks, liver weight and liver-to-body weight ratio were increased at the two higher dose levels. Overt toxicity was observed at the highest dose level after 10 and 15 weeks as evidenced by significantly smaller body weight. Urinary alkaline phosphatase and lactate dehydrogenase activities were elevated at 5, 10 and 15 weeks of PCB exposure and the kidney-to-body weight ratios were elevated at the 10 and 25 mg/kg dose levels after 10 and 15 weeks of exposure indicating nephrotoxicity. Hypercalcemia was present at the highest dose level after 5 and 10 weeks of exposure but serum calcium concentration was normal at 15 weeks. Serum triglycerides were significantly elevated after 5 weeks of exposure but were significantly decreased after 10 and 15 weeks of PCB exposure. Serum cholesterol was significantly elevated at the two higher dose levels at all three periods. The results demonstrate that PCB exposure effects calcium metabolism and bone morphometry and is nephrotoxic. (Copyright (c) 1989 Elsevier Scientific Publishers Ireland, Ltd.)