Factor VII deficiency is a rare disorder (1/500,000), with manifestations similar to those experienced by patients with haemophilia. Excessive bleeding during surgical procedure is prevented by factor VII administration. We report two cases of patients presenting a factor VII deficiency who were treated for oncological surgery. In the first patient with a severe congenital factor VII deficiency (8%), a continuous infusion of factor VII prevented the development of perioperative bleeding. In the second case, with a probably acquired factor VII deficiency (33%) related to a leiomyosarcoma, bleeding was prevented by a single preoperative factor VII injection.