Since the mid 18th century, a declining trend in age at menarche is observed worldwide until it stabilized at around 12-13 years of age for the last 40-50 years in developed countries. However, because of variation in the life style, genetics, and environment factors, the age at menarche still continued to vary especially in less developed countries. The knowledge of age of menarche is used to establish law about the age of marriage, age of consensual sex, abortion, family planning, rape and other aspects of female reproductive life. With emergence of HIV as one of major threats to mankind and teenage pregnancy as one of the major social problem, it is important to understand and promote healthy body habits for appropriate timing of menarche. Few studies were carried out in developing countries like Ethiopia earlier to find the age of menarche. The aim of this study was to determine age at menarche and to investigate its relation with body habits among adolescents and conducted in hope of helping the government to decide the appropriate age of children at which the topics like sex education, contraception and sanitary practices can be incorporated at school.