This study estimates the specification of aggregate production for Indonesia using the constant elasticity of subtitution (CES) production function. The data used in the is an annual data from 1976-2004. By linearized the CES production function, the general last square methods of regression (Wirh the Cochrane-Orcutt Interation Procedure) shows that the elasticity of subtitution between labor and capital is un-perfect which means that the elasticity of subtitution between labor and capital is un-perfect subtitution.This finding is relevant with the cobb-douglas production function as a special case of un-perfect subtitution production function