Despite many advances, cardiovascular disease remains the leading cause of mortality and morbidity in the United States. In general, environmentally or occupationally related diseases which affect the heart are most likely to arise either in the coronary vessels or in the myocardium, although this is frequently judged on clinical criteria without pathologic confirmation. The principal valvular heart disease, rheumatic endocarditis, is declining in incidence in the United States, due to the effective treatment of its etiologic agent, the beta hemolytic Streptococcus. Right ventricular dilatation, usually accompanied by thickening of the myocardium, frequently accompanies chronic pulmonary disease and thus is a complication of occupational lung disease of longstanding. The effect of the sympathetic nervous system to regulate the blood pressure leads inevitably to questions about whether environmental stress and/or psychoneurogenic mechanisms play a major role in a disease for which there is no uniformly accepted pathophysiologic mechanism.