Abstract: A portable heart monitoring apparatus incorporating unique structural and functional features. Electrodes carried on the apparatus capture electrical signals representing the functioning of a heart beating therewithin and provides sensible output indications corresponding to predetermined characteristics of the electrical signals and, hence, of the detected heartbeat. One of the sensible outputs provided is the selective actuation of either of two logic lights indicating whether the heartbeat is above or below respectively a predetermined beating rate. The unit is automatically turned on by merely holding the instrument in the user's hand and the selective actuation of the various operational modes may be conveniently made by selectively placing one of the hands's digits (such as the thumb) from one touch contact point to another. Part of the operation in the test mode involves the effective testing of the reserve battery power without actually loading the battery.