A longitudinal observation was carried out for 3 years on 252 cases with confirmed primary and secondary myocardial pathology. The disease development of the indicated patients was observed and followed up during that period, aiming at the precise and objective presentation of the state of the labour-physician expertise. The lost calendar sick days, concerning the main disease were considered the basic index of the temporary disability. Cut of the confirmed 252 cases with chronic myocardial pathology, 94 patients (37,9%) have been temporary disabled during the period observed. Up to one month sick leave had 22,62 per cent of the patients with common myocardial pathology, up to three months--11,90 per cent and to 6 months--2,78%. The higher number of cases with temporary disability was established in the group of postinflammatory diseases--54,86%. The lowest temporary disability was recorded with the primary cardiomyopathies, that quickly advanced into permanent disability. The data from the study show as well that permanent disability had developed in 28,17 +/- 5,55 per cent of the patients with chronic myocardial pathology.