A primigravid woman with multiple uterine leiomyomas was seen at 8 weeks' gestation with acute renal failure and hypertension. After placement of bilateral nephrostomy tubes, renal function improved and blood pressure normalized. The pregnancy was complicated by maternal abdominal discomfort, intrauterine growth restriction, and perinatal death. A myomectomy performed post partum revealed a 24.4 pound pedunculated leiomyoma compressing the right kidney and liver. Large uterine leiomyomas may cause obstructive nephropathy and renal failure in pregnancy.