Eighteen international cancer centres responded to a questionnaire designed to determine clinic practices regarding the management of Hereditary Non-Polyposis Colorectal Cancer (HNPCC). Areas covered include definition, clinical intakes, pre-genetic testing for microsatellite instability (MSI) or expression of mismatch repair (MMR) genes by immunohistochemistry (IHC), mutational analysis, consent practices, counselling, surveillance planning, and surgical decision making. In the absence of a firm evidence base, some management practices were variable, with local access to funding and other resources being influential. More consistent responses were evident for management practices with a stronger evidence base from previous clinical research. This document provides important information to guide the management of HNPCC patients, allow comparisons to be made between the approaches of various clinics to HNPCC families, and define management issues that need to be addressed in clinical research.