A decision support system (HEPASCORE) has been developed to optimize the application of objective criteria for qualitative and quantitative assessment of liver function; clinical and laboratory data are automatically processed, and conclusions are explained. Early recognition of abnormal liver states is performed according to a sequential approach, based at first on clinical rules utilizing data from history and physical examination, then confirming or denying the hypothesis by means of selected laboratory tests. Once an abnormal condition is defined, clinical severity can be evaluated by use of suitable scores, either prognostic or focused on major clinical complications. In addition, selected sets of biochemical tests can be used to score one or more functional aspects. Lastly, whenever quantitative estimates of residual liver function are requested, dynamic tests can be applied to measure meaningful parameters such as functioning liver mass and functional hepatic plasma flow. HEPASCORE has been successfully applied to exclude liver abnormalities in subjects at risk, to follow up liver patients, to predict the natural outcomes of severe liver diseases, to foresee the adverse effects of drugs undergoing first-pass liver extraction and the side effects of invasive procedures. While the proposals contained in the system could be further modified for specific needs, they reflect a satisfactory methodological approach, and the program serves as a useful support to decisions regarding the identification and functional evaluation of hepatopathies. The system was developed with Microsoft Access 7.0 and runs on a personal computer under Windows 95.