In four series of observations, 563 males with verified diagnoses of ischaemic heart disease (IHD) were examined. Assessment of the patients' psychological status was carried out using the Minnesota Multiphasic Personality Inventory (MMPI) and a clinical rating scale. A close correlation was established between cardiac pain syndromes and the psychological state of IHD patients. The most severe psychological changes were found in association with combined cardiac pain syndromes (angina pectoris and cardialgia). In cardialgia they were more prominent than in angina pectoris. In frequent anginal attacks, and in angina both at rest and on effort, psychological disturbances were observed much more frequently and were of a more profound nature (depression, hypochondria), than in rare attacks of angina, or in angina on effort alone. The least marked psychological changes were observed in IHD running a painless course. Possible cause and effect interrelations underlying these correlations are discussed. Attention is drawn to the necessity for a systematic approach to the treatment of IHD patients, including the use of psychotherapy and psychopharmacotherapy.