Abstract: An electro-mechanical heart compressor system for use in rendering first aid in cases of heart stoppage provides a constant-stroke-length, motor driven reciprocating plunger extending downwardly through a first or upper mounting plate. A second or lower mounting plate with uprights at the ends provides a support for a patient and adjustably holds above it the upper mounting plate in position with the plunger above a mark designating the proper location for the patient's heart. The reciprocation is provided by an electric motor acting through a crank and slotted yoke adjustably affixed to the shaft of the plunger, which shaft is held in guides.