EVINCE-I is an expert system for neuropsychiatric diagnostics implemented on a personal computer. It is developed to assess the possibilities of an expert system which models the procedures used for medical decision taking and data analysis by a neuro-psychiatrist when making a differential diagnosis in the domain of dementia syndromes. The knowledge of the system centers around detection of Alzheimer's disease, multi-infarct dementia and depression-induced dementia. EVINCE-I and the human expert were compared in their ability to diagnose 29 patients, i.e. 19 patients with early stages of dementia and 10 patients showing varying disorders except dementia. It is shown that EVINCE-I is able to detect dementia and its main causes, and produce diagnoses that agree with those of the human expert.