The purpose of tumour staging for colorectal cancer (CRC) is to help define clinical management, facilitate communication between physicians, provide a basis for stratification and analysis of treatment results in prospective studies, and provide some prognostic information for patients and their families. The World Congresses of Gastroenterology, Digestive Endoscopy, and Coloproctology, Working Party on staging for CRC studied six commonly used systems to review their strengths and weaknesses. Although it was concluded that defining a new staging system was unnecessary, it was recognized that there is a need to define a terminology to describe the full anatomic extent of spread of CRC. Furthermore, we note that there are several additional features, derived from both clinical and pathology information, which have had prognostic significance shown by appropriately constructed multivariate analyses and which can be used to formulate a more accurate prognostic index than that provided by a description of anatomical tumour spread. Thus the Working Party came to two principal conclusions. First, a standard format should be adopted for the collection of the essential data required for prospective studies, and we recommend the 'International Documentation System (IDS) for CRC' for this purpose. Second, a nomenclature which describes the full anatomical extent of tumour spread and residual tumour status in CRC has been defined and should be adopted, from which all currently used staging systems can be derived. We have called this nomenclature the 'International Comprehensive Anatomical Terminology (ICAT) for CRC'. In the event that these recommendations are adopted, we envision that there will be improved clarity in the documentation of treatment outcome for patients with CRC and improved communication of results derived from prospective studies. Furthermore, an acceptance of IDS and ICAT would set the scene to develop a prognostic index for individual patients with CRC by the expansion of anatomical clinicopathology staging information to include additional factors which have independent prognostic significance.