Primary hyperoxaluria is a rare congenital disorder characterized by large quantities of urinary oxalate with resultant nephrocalcinosis and nephrolithiasis and by deposits of calcium oxalate in other organs. Renal failure occurs early in life. Reports of unsuccessful renal transplantation attempts in this disorder underscore the need for antemortem diagnosis. Percutaneous bone biopsy is a relatively new procedure that is easily done at bedside, safe, and of potentially high yield in the demonstration of tissue oxalate. Three cases presented here show the characteristic histologic picture seen in this disease. In one case, the diagnosis was established by bone biopsy.