A technology assessment report on genetic testing for hereditary nonpolyposis colorectal cancer (HNPCC) was abstracted in the Health Technology Assessment Database . Genetic testing of HNPCC can reduce the number of surveillance colonoscopies and help target surveillance at high-risk patients. Studies of the effect of genetic testing of HNPCC on more substantial outcomes such as mortality are limited. Genetic testing requires pre- and post-test genetic counselling and written informed consent for both affected and at-risk individuals. Testing is not indicated for patients with sporadic colorectal cancer nor their family members, and not for mass screening of the general population. If germ-line mutation analysis indicates a deleterious mutation, genetic testing of at-risk family members can provide true positive and negative results. If no deleterious mutation is found in the affected person, genetic testing of at-risk family members will only provide inconclusive results.