Abstract: From July 1983 to July 1984, the menarcheal age of 3972 females (12 to 23 years old) in Yi Li Prefecture, Xinjiang Uigur Autonomous Region, was surveyed by the retrospective method, among them were 924 Kazaks, 864 Uigurs, 486 Sibos, 209 Hui nationality, 216 Mongols and 1273 Hans. The mean ages at menarche and their standard deviation were: 14. 37±1. 09 years for Kazak, 14. 34±1. 41 years for Uigurs, 14. 21±1. 05 years for Mongol, 13. 89±1. 32 years for Hui nationality, 13. 78±1. 02 years for Sibo and 13. 61±1. 11 years for Han. Most girls in each nationality have their menarche in July, August and September provided that there was fine weather and good nutrition. Nevertheless, a remarkable tendency of advance of menarcheal age was observed. By comparing the menarcheal age of those born in 1961-1964 with that of 1969 —1972, it was found that the advance of mean menarcheal age during eight years was: 2. 67 years for Hui nationality, 1. 9 years for Mongol, 1. 78 years for Sibo, 1. 64 years for Han, 1. 17 years for Kazak and 1. 13 years for Uigur, respectively.

Key words: Menarcheal age; National minorities