Since 1970, Seattle Fire Department paramedics have treated 5,120 victims of out-of-hospital ventricular fibrillation (VF). During the past decade, there was an impressive decline in the annual incidence of VF, probably reflecting a general reduction in age-adjusted mortality attributed to coronary heart disease. Since 1975, annual survival rates to hospital discharge fluctuated between 24% and 33%, averaging 28.9%. In spite of continuing efforts to improve basic and advanced life support, survival rates have not risen concomitantly. Since the early 1970s, average ages of victims have increased from 63.4 to 66.1 years (p less than 0.0001). Additionally, in survivors of VF arrest, habitual cigarette smoking has become much less frequent (48% versus 31%, p less than 0.0001). Longevity of VF survivors has improved in recent years, with 1- and 5-year survival rates increasing from 74% and 44%, respectively, for those resuscitated during 1970-1975 to 83% and 57%, respectively, for those resuscitated during 1982-1987 (p less than 0.0001). It is likely that medical or surgical therapy and improved hygienic measures have contributed to the better outcomes. The vast majority of resuscitated victims have not had symptomatic ventricular arrhythmias before VF. Accordingly, current efforts to control such arrhythmias will not have an important impact on the community incidence of sudden cardiac death. Successful strategies for further containment will likely be those that address the problem of coronary atherogenesis, although medical and surgical therapies may also have a role. Additionally, it is timely to evaluate the widespread use of automated defibrillators by persons other than emergency medical technicians or paramedics.