A tool for neurological and diagnostic testing comprises the combination of a stethoscope with a reflex hammer including a light. When mounted on the stethoscope head the reflex hammer extends beyond the head, without interfering with the normal use of the stethoscope. A handle, which may or may not be joined to the reflex hammer, is positioned on the flexible stethoscope tubing and provides a gripping surface for using the tool for neurological testing. One embodiment includes a light within the reflex hammer, so that a light is available for testing responses to light at the same time as checking other responses. The reflex hammer and light combination is adaptable for use with binaural and electronic stethoscopes, thus providing a convenient set of instruments within a single device. A detent on the handle provides an ergonomic grip, or a place for inclusion of indicia.