In order to assess the effects of age-related changes of serum dehydroepiandrosterone sulphate (DHEAS) and androstenediol (AED) concentrations on BCG vaccination throughout the puberty period, we matched 41 prepubertal (mean age 8.63+/-1.36 years, range 8-14 years) and 43 pubertal (mean age 13.8+/-1.31 years, range 10-16 years) schoolchildren who were PPD negative and free of disease or medication known to affect immune function. The tuberculin test was performed 8 weeks after vaccination and tuberculin response and hormone levels were compared between prepubertal and pubertal subjects. We found a higher tuberculin response in the pubertal group when compared with the prepubertal ones. The pubertal children had 79.1 per cent tuberculin positivity compared with 46.4 per cent of prepubertal children (p<0.05). Diameters of induration of the tuberculin test among prepubertal students vs. pubertal students were 9.5+/-3.8 mm and 11.9+/-3.7 mm, respectively (p<0.005). Pubertal stage, testis volume, and pubic stage were also found to have significant effects on tuberculin test results. No difference was observed between both sexes with regard to responses of the tuberculin test in either the prepubertal or the pubertal group (p>0.05). DHEAS and AED levels in the tuberculin-positive subjects were found to be significantly higher than tuberculin-negative ones (p=0.040 and p=0.046, respectively). Among both these hormones, only AED levels were correlated with tuberculin test responses. These results suggest that AED may play a role in the immunity to BCG vaccination and further immunological investigations are warranted to provide support for this idea.