With 847 girls of senior high schools in Maebashi and Takasaki, Gunma Prefecture, survey was performed on the time of menarche and physical growth, especially from the viewpoint of actual school health supervision. The average age of menarche was 13.06±0.93 years, which shows, with reference to previous reports, the tendency of its gradually becomimg earlier. As for the season of menarche, it is most frequent, irrespective of age, in July-August and April-May, followed by January. Since these periods correspond to vacation, feeling of liberation, that is, psychial factor, is assumed to have effect of a trigger. Comparison between the time of menarche and the permanent stature disclosed that the early pubescence group was characterized by long trunk and short legs, and especially by obesity. Out of stature, body weight, chest circumference and sitting height, it was the last whose development had closest relation with the occurrence of menarche. The sitting height at the time of menarche was almost constant at 80-82 cm independent of age and chronological year. Furthermore, in the course of adolescent physical growth, the annual increment of sitting height reached the peak at 0-2 years, and that of the lower limb length at 3-4 years before menarche. There after the latter began to decrease gradually, and the decrease became abrupt at 0-1 year before menarche. It is therefore highly probable that menarche may take place within a year when the annual increment of the lower limb lengh abruptly decreases after passing the peak. These findings can be used with advantage for actual sex education and school health program.