The epidemiological evidence for the cardio-protective effect of nut consumption is presented and reviewed. Four large prospective epidemiological studies of primary prevention of coronary heart disease are reviewed and discussed (Adventist Health Study, Iowa Women's Health Study, Nurses' Health Study and the Physicians' Health Study). Other studies of nuts and coronary heart disease risk are addressed. The combined evidence for a cardio-protective effect from nut consumption is summarized and presented graphically. The risk of coronary heart disease is 37 % lower for those consuming nuts more than four times per week compared to those who never or seldom consume nuts, with an average reduction of 8.3 % for each weekly serving of nuts. The evidence for a causal relationship between nut consumption and reduced risk of coronary heart disease is outlined using Hill's criteria for causality and is found to support a causal cardio-protective relationship.