The effects of ethylene glycol (EG) ingestion on calcium and phosphorus concentrations of bone and serum and changes in the urinary excretion of calcium, phosphorus, hydroxyproline, and citric acid were investigated in male albino rats. EG was administered po at a daily dose of 2 ml/kg for 6 days. Decreases were observed in calcium and phosphorus of bone, serum calcium, and urinary phosphorus and citric acid. Serum phosphorus, alkaline phosphatase activity, and urinary calcium and hydroxyproline were increased. The results indicate bone demineralization is an attempt to maintain serum calcium concentrations. The decreased citric acid excretion in the urine may explain the reason for the precipitation of oxalic acid with calcium, its deposition in the renal tubules, and its excretion in the urine. The hyperphosphatemia observed on EG administration was the result of the nephrotoxic effect of the glycol.