Abstract
Hereditary nonpolyposis colorectal cancer (HNPCC) families are frequently missed in the clinical practice setting. The events leading to the diagnosis of a new HNPCC family are described, with particular attention to the importance of a detailed and extended pedigree, and the delivery of pertinent educational and cancer control recommendations to family members. Clinical clues suggestive of HNPCC include young age at colon cancer onset (