The structural and informational content of clinical radiology reports was examined to develop a comprehensive representational schema of the concepts in the domain. The model involves several different conceptual levels, ranging from the high level description of the report to the lower level description of the clinical concepts contained in the reports and the specification of the terms used to express the concepts. The design of an adequate structured representation for the domain has important implications for the design of the electronic patient record, for the unification of different controlled vocabularies by enabling them to be mapped to one common representation, and for the facilitation of natural language processing of clinical reports so that coded data may be obtained.