The electrocardiographic examination of 38 male skiers, natives of the European North aged from 18 to 22 years was carried out during four seasons (September, January, March, July). We have found that the highest myocardial electrical activity was typical for the winter period. Seasonal changes in the electrical activity of the myocardium developed mostly in the interventricular septum and the basal parts of the heart, and the right heart compared with its left part.