Restoration of adequate spontaneous circulation after "arrest" and cardiopulmonary resuscitation (CPR) of 546 patients before and 460 patients after initiation of a CPR training course in a 500-bed city hospital is reported. Between January 1972 and June 1976, adequate circulation after CPR was present in 38.6% of patients before and 50.4% after training ICU nurses and house physicians in modern resuscitation techniques. Factors crucial to resumption of adequate circulation are: (1) CPR training of all hospital personnel so that effective CPR can be started immediately after recognition of an arrest situation, (2) production of a palpable pulse with closed chest cardiac massage, and (3) prompt effective therapy so that the time interval between arrest and resumption of adequate spontaneous circulation is short.