Abstract: Present paper studies the Economic Efficiency and Gain technologies. Most of the literature related to the measurement of economic efficiency has based its analysis either on parametric or on non-parametric Gain methods. This Article thus argues that, while Technique economy tends to be a powerful force, it is possible for concerns of Economic efficiency. The aim of this paper is to provide a critical and detailed review of both core Gain methods. In our opinion, no approach is strictly preferable to any other. Moreover, careful consideration of their main advantages and disadvantages, of the data set utilized, and of the intrinsic characteristics of the framework under analysis will help us in the correct implementation of these techniques. Recent developments in Gain techniques and economic efficiency measurement such as Bayesian techniques, bootstrapping, duality theory and the analysis of sampling asymptotic properties are also considered in this paper.