In the present study an attempt has been made to study the nutritional status of the Schedules Tribes of Rajasthan on the basis of body mass index. Cross-sectional data on 2928 samples belonging to both adolescent (8+ to 18+) and adult age groups (19 & above) were collected during the year 1999-2001. The data were collected following the Internationally accepted standards. All the populations show an increase in the mean values of BMI in both males and females with advancing age. High prevalence of undernutrition was observed in both adolescent boys and girls of the present study on the basis of BMI. The results of chronic energy deficiency grades also clearly indicated a high prevalence of thinness. Bhils show the lowest BMI than their counterparts in the other tribes. Mina males and females exhibit highest mean values of BMI at higher age groups.