DXplain is a computer program designed to provide quick, easy access to a large database of signs, symptoms, and diagnoses, and to remind the user of disorders which might be associated with a set of clinical features. The database used by DXplain includes many common and rare diseases,but should not be considered complete due to a number of causes, including but not limited, to a lack of complete coverage of all signs, symptoms, laboratory tests, and diseases, and inaccuracies in relationships of clinical findings to disease entities.