NEW FINDINGS What is the topic of this review? The purpose of this review is to summarize present knowledge of the function of the afferent nerves arising from the heart and the coronary and pulmonary arteries. Although there is abundant evidence that atrial receptor stimulation influences heart rate and urine flow, with little or no effect elsewhere, and that ventricular receptors are strongly excited only by chemical stimuli, there is still the erroneous belief that they act as a homogeneous group causing cardiovascular depression. What advances does it highlight? Coronary receptors deserve to be recognized as a potentially important additional group of baroreceptors. Stimulation of pulmonary arterial baroreceptors at physiological pressures causes reflex vasoconstriction and could have a hitherto unacknowledged important role in cardiovascular control, for example in exercise. Although there has been a tendency to regard cardiac and pulmonary receptors as a single population of 'cardiopulmonary receptors', this cannot be justified as the various receptor types all induce their own particular pattern of responses. Stimulation of atrial receptors increases activity in sympathetic nerves to the sino-atrial node, causing tachycardia, but there is no effect on activity to the myocardium or to most blood vessels. Renal nerve activity, however, is decreased, and secretion of antidiuretic hormone is inhibited, causing diuresis. Ventricular receptors induce a powerful depressor response, but only in response to abnormal chemical stimulation and possibly to myocardial injury. Coronary arterial receptors function as baroreceptors, but have a lower threshold and a more prolonged effect than other baroreceptors. Pulmonary arterial baroreceptors induce vasoconstriction and respiratory stimulation at physiological pressures and may be of importance in mediating some of the responses to exercise, as well as in hypoxic conditions.