Arrhythmias and sudden death represent striking features in the natural history of thalassemia major. Antiarrhythmic treatment, however, does not appear to change the clinical course. During recent years the disease's therapeutics approach has undergone a substantial evolution, being more adequate the transfusional regimens as well as more effective the iron chelation therapy through subcutaneous infusion of deferoxamine. The aim of the present study was to determine possible influences exerted by the current treatment upon disease's arrhythmic disorders. Thirty patients of both sexes were enrolled in the study. The age ranged from 9 to 24 years. No congenital or acquired heart diseases were present. Each patient underwent concentrated red cell transfusions (in order to obtain pretransfusional hemoglobin levels of 10-11 g%), and iron-binding therapy through continuous subcutaneous microinjection of deferoxamine 40-50 mg/kg/day (6-8 hours/day, 6 days/week). Patients were divided in 2 groups: the first group (group A) comprising the 16 patients with good therapeutic compliance and regular pharmacological regimen; the second group (Group B) including the remaining poorly compliant 14 patients. The following parameters were analyzed: age, average hemoglobin levels during the last year, total amount of red cell transfusions, ferritin levels, starting age of iron-binding therapy. Moreover, each patient underwent 24-hour ECG Holter monitoring. Age (Group A: 18 +/- 4.6; Group B: 14 +/- 2.7; p < 0.02), total amount of transfusions (Group A: 272 +/- 73; Group B: 211 +/- 44; p < 0.03), and ferritin levels (Group A: 1697 +/- 860; Group B: 2908 +/- 730; p < 0.002) proved to be significantly different in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)