Milk-of-calcium urine associated with hydronephrosis is rare, with only 8 unilateral cases reported previously. We report the first case of bilateral occurrence. Upright films are necessary for making the diagnosis. Although previous reports indicate that the involved kidney has little or no function our patient had only slight impairment of renal function. Nephrectomy should not be done without evaluation of renal function, since some function may be preserved by removing the obstruction that is associated with milk-of-calcium urine and hydronephrosis.