&NA;Familial adenomatous polyposis coli is a heterogeneous disease with respect to genetics as well as its colonic polyposis and cancer phenotype. The authors report a family with variation in phenotypic expression of polyps ranging from isolated polyps to florid carpeting of the entire colonic mucosal surface. In addition to early‐onset colonic cancer, a patient with isolated polyps had a seminoma and subsequently developed gastroesophageal cancer. His son, also with isolated colonic polyps, manifested a pararectal rhabdomyosarcoma. The significance of these variations can only be assessed fully through the study of cancer of all anatomic sites in many additional families.