The system includes arranging diseases, symptoms, and questions into a set of related disease,symptom, and question structures, such as objects or lists, in such a way that the structures can be processed to generate a dialogue with a patient. The structure based system organizes medical knowledge into formal structures and then executes those structures on a structure engine to automatically select the next question. Patient responses to the questions lead to more questions and ultimately to a diagnosis. The system comprises a computer which is provided with a list of diseases, each disease associated with a list of symptoms. The computer is configured for selecting one of the symptoms to be a focus symptom based on a predetermined criteria and for evaluating the focus symptom to establish the symptom, the established symptom contributing a weight to the diseases having the established symptom. The system is additionally adapted for selecting one of the symptoms to be a focus symptom from the list of symptoms associated with a selected one of the diseases and for evaluating the focus symptom to establish the symptom, the established symptom contributing a weight to at least the selected disease having the established symptom. The computer is further configured for repeating the selection and evaluation of the focus symptoms until the accumulated weights for a disease reach or pass a threshold so as to declare a diagnosis.
