Hemodialysis catheter patency is regularly maintained by high-concentration heparin filling, according to manufacturer's recommendation. Surprisingly, there are only few reports on serious bleeding complications in children on dialysis. A case of serious, life-threatening hemorrhage in a child after tunneled peritoneal catheter removal because of hemodialysis catheter heparin lock flushing is described. Discussion of the literature data is presented. Further investigations are needed to develop the guidelines for pediatric dialysis catheter care, including the optimal concentration for heparin lock as the possible heparin alternatives, but until that moment, previously suggested guidelines to prevent hemorrhagic complications in dialyzed children should be emphasized.