This paper considered relationships of the somatotype/body composition to ages at take-off and peak velocity in height, and height maturity (percent adult height). The subjects consisted of 195 girls and 213 boys from junior height school at Tsukuba. The somatotype was estimated according to the anthropometric method of Heath-Carter. Percent body fat was assessed by the method of bioinmpedance. Ages at take-off/peak velocity in height, and adult height were estimated by BTT method from successive 6 years data during primary school ages. Dominant somatotype of a child was defined as a somatotype component rating at least 0.5 points higher than either of the other two component ratings. Girls showed the endomorph and boys the mesomorph as their representative somatotype components. Incidence of components of endomorph, mesomorph and ectomorph were of 54.7%, 9.5% and 35.7% for girls and were of 9.9%, 66.1% and 24.1% for boys, respectively. Although the correlation of the estimated PHV age to observed one was moderate (r=0.672 and r=0.577 for girls and boys) from an analysis of another sample, endomorphy girls tended to early-maturing girls. ANOVA resulted in no significant differences for means of ages at take-off/peak velocity, estimated adult height and height maturity among somatotype components for boys. Endomorphy girls showed earlier ages at take-of and peak velocity than ectomorphy girls. Similar results were obtained from the analysis of percent body fat. Percent body fat was correlated negatively to ages at take-off/peak velocity for girls at r = -0.408 and -0.450, respectively.