Data on 1350 Nellore sheep of 2, 4, 6 and 8-teeth age, reared under field conditions in 12 mandals of Chittoor district of Andhra Pradesh were utilized for development of prediction equations and study the phenotypic association among body measurements and body weights. The coefficients of correlation between body weight with the height at withers, chest girth, paunch girth, hip width and body length were positive and high in magnitude in both males and females in majority of the age groups studied. Step-down regression equations were fitted to predict the body weight based on biometrical measurements at different ages. The height at withers, chest girth, paunch girth, hip width and body length have contributed significantly to the expression of body weights at the majority of the ages studied. High coefficient of determination (R2) value was observed in males at 6 and 8-teeth age as 88 per cent, while in females 50 per cent at 2-teeth age.