We report observations on children with the unusual combination of superior vena cava syndrome in infancy followed by communicating hydrocephalus. Following retrospective review of hospital discharges at a tertiary children's hospital, three children were identified in a 13-year period. Two term infants were treated with extracorporeal membrane oxygenation for pulmonary failure associated with congenital diaphragmatic hernia. These infants had septic complications of central venous lines. A post-term infant required reconstruction of the superior vena cava following cannulation for cardiac bypass surgery to repair transposition of the great vessels. Thrombosis occurred and was followed by the sequential development of superior vena cava syndrome and communicating hydrocephalus. The findings in these patients suggest that communicating hydrocephalus may be caused by superior vena cava syndrome. This is an unusual complication of therapeutic manipulation of the heart and great veins. Cerebrospinal fluid shunting may be required.