Abstract
In India, we compute the sex ratio in terms of number of females per thousand males. Among the various components of population composition, sex composition holds a prime place in the context of demographic composition of any region. The balance between the two sexes affects the social and economic relationship within a community. In developed countries, where nursing facilities and medical care are developed, the male mortality rate is higher than the female mortality rate at all ages. But in less developed countries, more females die in comparison to the males. The most desirable and theoretically expected primary sex ratio genetically is 50:50. Arunachal Pradesh in India which is dominated by scheduled tribes [66.78%of total population], despite being an egalitarian society has been experiencing a high sex ratio in tribal society. This paper, therefore, seeks to examine the feature and trend as well as the overall pattern and factors responsible for high sex ratio in Arunachal Pradesh.