The Amsterdam criteria are a set of diagnostic criteria used by doctors to help identify families which are likely to have Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC). The Amsterdam criteria arose as a result of a meeting of the International Collaborative Group on Hereditary Non-Polyposis Colon Cancer in Amsterdam, in 1990. Following this, some of the genetic mechanisms underlying Lynch syndrome were elucidated during the 1990s and the significance of tumours outside the colon, such as those of the endometrium, small intestine and ureter, became clearer. These changes in the knowledge of the syndrome lead to a revision of the Amsterdam criteria and were published in Gastroenterology journal in 1999. (en)