The median menarcheal age of 107 girls adopted from India by families in Sweden was 11.6 years, which was significantly lower than in Swedish and most Indian studies. Five girls had menarche before the age of 9 years, the earliest at 7.3 years. Those who arrived at a later age had earlier menarche. No differences in menarcheal age were found with respect to geographic origin. The reasons for the earlier pubertal maturation are not clear. Factors associated with the rapid transition from an underprivileged to a privileged environment are probably involved, besides genetic determinants. The serious medical, social and emotional consequences of very early pubertal development necessitate further clarification of the underlying mechanisms.