This paper sets out a series of descriptive conceptual models of colorectal cancer and its detection, diagnosis, treatment and follow-up. The paper is based on an update of the work reported in Trueman et al1 and is intended to be useful for health economic modellers and other researchers working in the area of colorectal cancer evaluation. In particular, it is intended that this paper should provide a consistent conceptual basis for the development of health economic models of colorectal cancer services and technologies in the future. The paper is set out as follows. Section 1.2 details the methods used in the development of these conceptual models. Sections 1.3 presents the key disease-specific factors associated with colorectal cancer. Section 1.4 presents a series of problem-oriented conceptual models of colorectal cancer service pathways.