The aim of this study was to provide normative data for the onset and tempo of puberty in healthy boys. The analyses are based on data that were collected and evaluated biannually on 1112 Turkish school children aged from 8 to 18 years and a subsample of 30 boys who had reached final height (FH). The data were analyzed cross-sectionally in the total group and longitudinally in the subsample. Mean age and height (Ht) at onset of puberty were 11.6 +/- 1.2 years and 146.1 +/- 7.7 cm, respectively. Peak height velocity (HtV) was 10.1 +/- 1.6 cm. Total pubertal height gain was 26.4 +/- 4.3 cm. The duration of puberty was 4.9 +/- 0.6 years. Height at onset of puberty was positively correlated with FH (p < 0.0001) and with duration of puberty (p=0.03). Body mass index at onset of puberty correlated negatively with age at onset of puberty (p < 0.009) and with the duration of puberty (p=0.05) but not with FH. In conclusion, these results provide normative data for Ht and HtV for each testicular volume stage for boys in puberty. Height at onset of puberty is the most important determinant of FH. There is no secular trend for the onset of puberty. Weight does seem to affect the onset and tempo of puberty but not FH.