Adrenal steroid production was evaluated in 12 thalassemic girls aged between 18 and 22 years and at stage P1 of sexual maturation according to Tanner. The values found in these patients were compared with those in 12 normal girls of the same age at stage P4-5 of sexual maturation. Pregnelone, dehydroepiandrosterone, dehydroepiandosterone sulfate, progesterone, 17-OH-P, androstenedione, testosterone, dihydrotestosterone and estradiol were found to be significantly reduced (p less than 0.001) in the thalassemic group, while cortisol levels showed a slight but not statistically significant reduction. Plasma ferritin levels were greatly increased and showed a highly significant (p less than 0.001) correlation coefficient when plotted against each hormone. The present results suggest that the impaired adrenal function plays an important role in determining the delayed sexual maturation almost always present in the thalassemic patients and that this disorder may be due to iron overload.