Lynch syndrome is the most common cause of hereditary intestinal cancer, with a 30-70% risk of colorectal cancer (CRC). Prevention of CRC by colonoscopy in family members with Lynch syndrome is highly effective; therefore, it is important to trace as many people with this syndrome as possible. Criteria have been developed in the Netherlands to increase detection of hereditary colorectal cancer in a practically feasible and cost-effective way. Based on these criteria, the pathologist can perform microsatellite instability testing in patients recently diagnosed with CRC. The criteria are: CRC under the age of 50, second CRC under the age of 70, or CRC under the age of 70 with a concurrent or previous malignancy associated with Lynch syndrome. For family members and patients diagnosed with CRC more than a year ago, a digital test can be used to determine whether genetic counselling by a geneticist is indicated (www.umcn.nl/verwijzers).