Hereditary nonpolyposis colorectal cancer is the most common form of hereditary colorectal cancer. Occasionally, the presentation of colorectal cancer may be at an early age when parents may be unidentified obligate carriers. The risk of colorectal cancer increases with increasing age, even in inherited disease. Therefore, it is important to screen parents of patients presenting at a young age and to obtain a complete pedigree to identify and screen those who are at risk. Two such families where the index case presented at a young age were encountered in our practice and both their mothers were found to have colorectal cancer on surveillance colonoscopy. We recommend that parents of the index cases should be screened and more detailed family pedigree obtained when patients present at a young age with colorectal cancer.