• Infection of a central venous thrombus is a serious but rarely recognized complication of the use of central venous catheters in children. We report the cases of seven children with persistent bacteremia or fungemia in which central venous thrombosis was demonstrated by ultrasonography after removal of the catheter. All patients had signs and symptoms of infection, but only one had clinical evidence of central venous stasis. Bacteremia persisted from 6 to 35 days. Infection did not resolve in any patient prior to catheter removal, and five patients had positive blood cultures for 5 or more days after removal of the catheter. Six patients, including all who survived, were treated parenterally with antibiotics for more than 28 days. Two patients died; neither death was directly attributable to infection. Central venous thrombosis should be suspected in patients with persistent catheter-related bacteremia. Optimal treatment of this problem is not yet known.