Congenital diaphragmatic hernia (CDH), a herniation of the abdominal contents through a defect or hypoplasia of the diaphragm, is a relatively common, severe congenital anomaly. Here we present the first case of two siblings with possibly isolated sac-type CDH and with a suspected genetic etiology. Although sibling recurrence of isolated CDH is rare, the incidence is higher than in the general population. Additionally, the second child had a more severe respiratory disorder than the first child. It is to be noted that siblings of children having isolated CDH are at risk for CDH, and prenatal evaluation should be considered individually.