Background: Mid-upper arm circumference (MUAC) is one of the simplest and easiest measures for large-scale screening programme for assessing undernutrition, especially among children. MUAC-based nutritional survey is easy to implement at the community level by the health workers or volunteers after minimum training.

Methods: The present cross sectional study was done among Bauri and Santal children of Purulia, West Bengal, India. A total of 1013 children (Bauri = 499 and Santal = 514) aged 2-6 years were measured for MUAC. The normalized MUAC for age by z-scores were calculated using LMS method.

Results: The age, sex and community specific sample distributions were prepared. Mean MUAC increased with age (except among Santal boys at the age of 6 years). The girls had higher median MUAC than boys at all ages except at 2 years. Prevalence of MUAC-based undernutrition (following WHO) was highest at the age of 3 years for boys (61.7 %) and girls (36.5 %). Similarly, prevalence of undernutrition was highest (48.6 % and 47.4 %) among Santal boys and girls at the age of 6 and 3 years, respectively. Significant sex difference (age combined) in prevalence of undernutrition was observed among Bauris (χ2= 20.54, df= 8, p< 0.001) and Santals (χ2= 6.71, p< 0.05).

Conclusion: High rate of undernutrition was observed among these children.. Our study clearly revealed that the median MUAC of children were lower than two standard references at all ages.