Hypogonadotropic hypogonadism (HH) is common (40%) in beta-thalassemic patients. Taking into consideration that in HH non-thalassemic patients we obtained good results in pubertal development using hCG treatment (1500 IU every 6 days), 10 HH thalassemic subjects (14 5/12 -17 yr, all with bone age greater than 13 6/12) were treated with the same regimen. In 5 of these patients purified FSH (75 IU every 3 days) was added to hCG in order to evaluate the FSH effect on testosterone (T) response (Group 1 was given hCG alone, Group 2 hCG + FSH: Profasi HP and Metrodin Serono). To evaluate the kinetics of testosterone response, plasma level of T was determined basally and 1, 2, 4 and 6 days after hCG injection. This dynamic study and a clinical examination were carried out at the beginning of treatment and at the 4th and 12th month after. Results obtained in the first group confirmed our previous data from non-thalassemic HH patients: in fact, after 12 months of therapy a stage G2-G3 was reached. In the second group, however, testis size and testosterone secretion were significantly higher than in the first group.(ABSTRACT TRUNCATED AT 250 WORDS)