An important component in the rehabilitation program of patients with cardiac disease is assisting them in resuming sexual activity. In many cases, cardiac disease creates fear, particularly in the spouse, that sexual activity will trigger a cardiac event. Assessment of the possibility that sexual activity may lead to cardiac disease has been aided by advances in the study of triggers of cardiovascular disease. The acute onset of cardiovascular disease has, in many cases, proved to result from the exposures and activities of patients. Nonfatal myocardial infarction, sudden cardiac death, stroke, transient myocardial ischemia, and most arrhythmias have a marked peak during the period between 6:00 A.M. and noon. Wake-time-adjusted data indicate that peak occurrence follows waking and rising. In addition to this marked dependence of disease onset on time of day and awakening, it has been established that there are numerous other triggers of cardiovascular events. For nonfatal infarction, the triggers of heavy exertion, anger, sexual activity, and awakening account for approximately 17% of all cases. Other triggers are still being identified. A new epidemiologic method, the case-crossover method, has greatly enhanced identification of triggering. Regular exertion can reduce the incidence of triggering. It is possible, though unproved, that an acute event can be triggered by rupture of a vulnerable atherosclerotic plaque. With regard to sexual activity, the low absolute risk generated by a potential trigger is useful information with which to reassure patients.