In familial adenomatous polyposis coli (APC) it is possible to detect APC carriers either by research of bilateral congenital hypertrophy of the retinal pigment epithelium (CHRPE) or by genetic diagnosis (APC gene is localized in 5q21). These detections were performed in 33 patients of four families with the same positivity for genetic typing (11 patients) or for CHRPE (11 patients) which thus avoided annual coloscopy.