The brain receives and catalogues myriads of information from within and without the organism. These inputs promote neural integration of bodily function through a multiplicity of cybernetic feedback loops. Higher nervous activity shapes the contours of perceived well-being and determines the course and progress of disease. Behavioral and neural factors play an important role in cardiovascular function and are especially relevant to the problem of sudden cardiac death (SCD). Clinical data attesting to the role of biobehavioral factors in SCD derive from a diversity of sources. It has long been known that bereavement increases the prevalence of cardiac fatality. Business failure rates are strongly related to increased mortality among persons aged 55 and over. Recession in economic activity, with increasing unemployment, is associated with augmented death rates from ischemic heart disease. In extensive surveys conducted among London civil servants, Rose and Marmot found not only the level but the type of employment to be a factor determining coronary heart disease mortality. Blue collar workers had a 3.6 times greater chance of dying from heart disease than an age-matched population in the higher ranks of civil service. A man's employment status was a stronger predictor of risk for dying from coronary heart disease than any of the usual risk factors, such as smoking, blood pressure, height-weight ratio, leisure time activities, glucose tolerance, or plasma cholesterol. Operation of behavioral factors is also suggested by the time of occurrence of sudden death. Among 3, 983 men followed for more than 30 years, Rabkin and co-workers observed an excess proportion of fatalities on Mondays. No such pattern was noted for cancer mortality. Not only the day of the week but the time of day appears to be a factor. Muller and co-workers found a significant preponderance in the occurrence of myocardial infarction and sudden death from 6:00 AM to noon. They could not implicate operation of circadian rhythm, but suggested a role for augmented autonomic neural discharge associated with early morning activities following waking from sleep. The longitudinal epidemiologic studies of the Health Insurance Plan of New York (HIP) have indicated an important association between behavioral and psychologic factors and the prevalence of sudden cardiac death. The level of education was a critical determinant of fatality. Patients who had less than 8 years of formal schooling and exhibited complex ventricular premature beats during the single hour of heart rhythm monitoring experienced a three-fold greater occurrence of sudden death compared to better educated men with the same level of ventricular arrhythmia. Psychologic variables were identified which preempt the role of education as risk indicators for sudden fatality. In these patients, a lack of education ceased to carry risk for sudden death when social isolation and a high degree of life stress were factored into the analysis.