The purpose of the present study was to find out the effect of yoga practice on mental health and study skills among school children of Tamilnadu.  For this purpose, ninety male adolescent studying in socially backward region, with the age group of 15 to 17 years who were studying in Nandanar Boys Higher Secondary School, Chidambaram (Cuddalore District), Government Boys Higher Secondary School, Vallalapatty, Madurai (Madurai District) and Government Boys Higher Secondary School, Thiruvannamalai (Thiruvannamalai District), were chosen as subjects. They were divided into two equal groups, each group consisted of forty five subjects, in which experimental group - I underwent yoga practice and experimental group - II acted as control that did not participate in any special activities apart from their regular curricular activities.  The training period for the study was five days (Monday to Friday) in a week for twelve weeks.  Prior and after the experimental period, the subjects were tested on mental health and study skills. Mental Health was surveyed by Jegadheesh Srivastava Mental Skill Questionnaire and Study skill was surveyed by M. Kanchana study skill inventory.  The Analysis of Covariance (ANCOVA) was applied to find out any significant difference between the experimental groups and control group on selected criterion variables.  The result of the study shows that the yoga practice group was significantly improved the mental health and study skills when compared with the control group.