A free text decision support system (DSS) has been constructed for health care professionals that allows the analysis of complex medical cases and the creation of a diagnostic list of potential diseases for clinical evaluation. The system uses a PC-based text management system specifically designed for desktop operation. The texts employed in the decision support package include The Merck Manual (published by Merck Sharpe & Dohme) and Control of Communicable Diseases in Man (published by the American Public Health Association). The background and design of the database are discussed, along with a structured analysis procedure for handling free text DSS systems. A case study is presented to show the application of this technology and conclusions are drawn in the summary that point to expanded areas of professional interaction and new frontiers yet to be explored in this rapidly progressing field.