This paper reviews the association between a vegetarian diet and a number of risk factors for cardiovascular disease investigated in a series of epidemiological and experimental studies. Ninety-eight Seventh-day Adventist "vegetarians" were similar to 113 Mormon omnivores for strength of religious affiliation, consumption of alcohol, tea and coffee and use of tobacco, but were significantly less obese and had significantly lower blood pressures adjusted for age, height and weight. A random sample of forty-seven Adventist vegetarians had significantly lower home blood pressures, serum cholesterol levels and blood pressure responses to a cold-pressor test than Mormon omnivores carefully matched for age, sex and Quetelet's index. In a controlled dietary intervention study mean systolic and diastolic blood pressures and serum cholesterol fell significantly during feeding with a vegetarian diet--an effect unrelated to changes in other lifestyle factors. Dietary analysis indicated that a vegetarian diet provided more polyunsaturated fat, fibre, vitamin C, vitamin E, magnesium, calcium and potassium and significantly less total fat, saturated fat and cholesterol than an omnivore diet. There was no evidence for a difference between vegetarians and omnivores in levels of catecholamines, plasma renin activity, angiotensin II, cortisol or serum and urinary prostanoids.