Chest pain is frequently a prominent symptom of the hyperventilation syndrome (HVS) and must be distinguished from angina pectoris due to coronary atherosclerotic heart disease (CAHD). The association between hyperventilation and chest pain may be apparent if psychoneurotic traits or anxiety are present. Many patients with HVS are not overtly anxious or neurotic, but in the great majority, a careful history and physical examination will indicate whether chest pain is due to HVS or CAHD. The failure to make this clinical differential diagnosis, which often leads to unnecessary coronary angiography, should not be as frequent as generally experienced. Fifteen of 95 consecutive patients had chest pain and additional typical HVS symptoms. Reassurance and detailed explanation about the cause of the chest pain gave significant relief, so that all patients were less symptomatic 24 to 44 months later, and none had developed new signs or symptoms to suggest that symptomatic CAHD had been overlooked. The risk and expense of coronary angiography was avoided.