Dyspnea may form a differential diagnostic symptom to chest pain in ischemic heart disease (IHD) but may also precede angina pectoris (AP) as a manifestation of IHD. In the Primary Preventive Trial in Göteborg the occurrence of AP and its relation to dyspnea has been studied in a random population sample of men aged 47-54 years at entry to the study and followed for 4 years. In the corss-sectional study dyspnea was reported in 21% of the total population and in 70% of the angina population. Dyspnea at entry to the study was reported in 36% among cases who developed AP along during the follow-up time and in 35% among cases who developed AP associated with myocardial infarction. The dyspnea was not related to smoking habits or to low grade of physical activity. The report of dyspnea before chest pain in IHD may be due to misinterpretation in early cases. On the other hand it is also known that intermittent left ventricular failure coincident with attacks of myocardial ischemia will give a subjective feeling of dyspnea. According to our study there is a definite association between AP and dyspnea. In some cases dyspnea precedes AP whereas in others the chest pain precedes the dyspnea. The symptom dyspnea also carries important prognostic information in IHD.