A cross sectional study was undertaken to examine the body composition including fat patterning among 1012 Santal children, aged 5-12 years, in Puruliya district of West Bengal, India. The anthropometric variable measured included height, weight and skinfold thickness of triceps and subscapular. The body mass index (BMI) was also calculated. The measurements were used to estimate body fat percent (%BF) and fat-free mass (FFM) from skinfolds. Fat mass and FFM were each divided by height squared to produce the fat mass index (FMI) and fat-free mass index (FFMI). Maximum gaining of %BF and FFM was found at ages 11-12 years in both sexes. Difference of-FFM between 5 and 12 years of age was found to be highest in girls (18.7 kg) than in boys (14.92 kg). Body fat percentage of girls was significantly (p < 0.05) higher (except in 8 and 9 years old) than that of boys. FMI and FFMI of girls showed different pattern than that of boys. FFM and %BF showed significant (p < 0.01) relationship with all anthropometric variables. Results suggests a clear evidence of sexual dimorphism in fat patterning; girls showing a greater subcutaneous adiposity in comparison with boys. FMI and FFMI, both indices indicate an age-and sex-related variation among Santal children. The data of the present study could be serving as reference data in other studies of Santal children.