The hepatic artery thrombosis (HAT) is the most serious complication after pediatric liver transplantation. Most of the cases will need a retransplantation. Multiple factors are keeping in discussion as causes of this complication: Rejection, two or more arteries, complex vascular reconstruction, etc. This article describes our experience with this complication and the prophylactic treatment. From January 1986 through April 1991, 62 orthotopic liver transplants were performed on 48 pediatric patients with a mean age of seven years. The incidence of hepatic artery thrombosis was 19 per 100, increasing when recipients were less than three years and less than 15 kg (23.8 per 100). Forty six cases were rearterialized with end-to-end anastomoses, ten were rearterialized by directly anastomosing them to the recipient aorta and six with iliac artery graft. We use in the last 38 consecutive patients prophylactic heparin during two weeks after transplantation (300 u/kg/d) following with antiaggregants. There were eleven patients with hepatic artery thrombosis, one of them had two episodes in both grafts. We perform a retransplantation in eight patients, two died waiting a new graft and one exceptional patient is out of the clinic with normal liver function and without regraft. Seventeen grafts had two or more arteries from aorta, ten with branches from superior mesenteric artery and five from gastric artery. One graft had a triple hepatic artery and another one was a common hepatic artery from superior mesenteric artery.(ABSTRACT TRUNCATED AT 250 WORDS)