Literature suggests that not only homozygotes but also heterozygotes for ataxia-telangiectasia have a high incidence of cancer, probably due to an impairment in DNA repair. The most frequent associations are with breast, lung, bladder, prostate and stomach tumors, while no correlation with colorectal cancer has been demonstrated. The affected family reported in this paper seems to have a high incidence of gastrointestinal tract tumors, including the colorectal ones.