Marjolin's ulcer is the malignant transformation of a scar, usually as a squamous cell carcinoma. An uncommon presentation form is from a laparostomy scar. A 49-year-old patient that had a laparostomy during the treatment of a necrohemorrhagic pancreatitis in 1987 complained 13 years later of a 20-cm ulcer on the laparostomy scar. A resection of the abdominal wall including the ulcer and a segmental transverse colectomy were performed because of infiltration by an invasive squamous cell carcinoma. Ten months later, axillary lymphadenectomy was performed because of lymph node metastasis. Currently, the patient is free of disease. Lymph node infiltration is frequent in squamous cell carcinoma on Marjolin's ulcer and survival is not good. Prophylaxis of this disease includes meticulous care of wounds, with early skin grafts when required and treatment of infections.