The purpose of our work was to study late cardiac complications after treatment for Hodgkin's lymphoma (HL) in children and adolescents. Methods: Sixty-seven patients were examined in the long term (>5 years) after chemoradiotherapy for HL according to two different programs of treatment (groups I and II). Mean total doses of radiotherapy (RT) to the mediastinum were 37.2 and 28.9 Gy, respectively. The status of the heart was assessed at the mean age of 22.7 years with electrocardiography (ECG) and echocardiography (EchoCG). Mean terms of follow-up were 16.4 and 9.5 years for group I and group II, respectively. Results: Incidence of ECG changes was equal between the groups (88% and 90%). The prevalence of signs of valvular calcifications and fibrosis was 70.9% after mediastinal doses ≥30 Gy, and 16.6% after lower doses (p = 0.002). Those changes led to considerable valvular dysfunction in four patients. EchoCG signs of pulmonary hypertension were seen in 33.3% patients of group I versus 4.8% in group II (p = 0.047). Pericardial effusion was observed in 7.4% and 5.1%, respectively (p = 1.0). Left ventricular ejection fraction decreased slightly only in two patients (one in each group). Conclusions: The RT mediastinal dose level is the important risk factor of late heart complications. Nevertheless, the differences in the rate and severity of those complications between the groups should be viewed with caution because of differences in the age at baseline and in follow-up terms. The survivors of HL should undergo life-long regular examinations of the heart status. © 2019, Mary Ann Liebert, Inc., publishers 2019.