Colorectal carcinoma rarely affects children and has a dismal prognosis with 5-year survival rates as low as 2.5%-7% despite apparently radical surgery. Here we report the case of an adenocarcinoma of the sigmoid colon in a 15-year-old girl preceded by uncertain abdominal complaints of 5 years' duration. Pathological work-up revealed a tumour with lymph node metastases (pT3NI). Immunohistochemical evidence of p53 overexpression by the tumour cells raised the suspicion of an underlying Li-Fraumeni syndrome. In addition, there were aphthoid ulceration, fissuration of the non-tumorous mucosa, along with a mixed transmural infiltrate composed of macrophages, eosinophils, and non-typical giant cells, which were compatible with simultaneous Crohn's disease. Anamnestic data concerning the occurrence of idiopathic inflammatory bowel disease or colorectal carcinoma in the patient's relatives were non-contributory. The present results suggest a possible relationship between Crohn's disease and colon cancer due to the defective p53 gene product.