Despite the many possible modes of presentation, congenital anomalies of the inferior vena cava are increasingly being found in asymptomatic patients. Although plain chest radiography may reveal enough suggestive signs, the diagnosis is usually confirmed by ultrasound, computed tomography and magnetic resonance imaging. The authors present a case of infrarenal absence of the inferior vena cava that presented as a retroperitoneal mass and discuss the embryology and clinical implications of this unusual entity.