We report a fetal bilateral renal agenesis in a woman suffering from insulin-dependent diabetes mellitus. Early diagnosis of this lethal congenital anomaly allows well-timed termination of pregnancy. Transvaginal sonography in combination with color flow mapping render possible an accurate diagnosis of bilateral renal agenesis. Sonographic and color flow mapping features of the above described malformation as well as invasive diagnostic possibilities and causes of renal agenesis in maternal IDDM are discussed.