A cross-sectional study was undertaken to determine anthropometric profile and nutritional status based on body mass index (BMI) of adult Bathudis, a tribal population of Orissa, India. A total of 409 adult (aged >18 years) Bathudis of three villages of Anandapur, Keonjhar District, Orissa, India, were studied. Anthropometric measurements including height, weight, circumferences and skinfolds as well as BMI and waist-hip ratio (WHR) were measured. Overall, the extent of undernutrition (BMI < 18.5) was found to be very high (57.9%). Moreover, there was a significant (chi(2)= 8.09674, P = 0.01745) difference in the prevalence of undernutrition between men (52.7%) and women (64.5%). In conclusion, this study demonstrated that the prevalence of adult undernutrition was found to be very high among the Bathudis, a tribal population of Keonjhar District, Orissa. These rates were much higher than those found in several tribal populations from other parts of India. Therefore, immediate nutritional intervention programs are needed for implementation among Bathudis. Moreover, further research is needed not only among this ethnic group but also other tribal populations of India to fully understand the causes and consequences of adult undernutrition.