Abstract: The traditional approaches could not fully rank all the DMUs in interval DEA because the efficient DMUs have the same efficiency scores. In order to solve this problem, we combined the discriminant analysis of ratios (DR) method with interval DEA so as to establish a new approach: the interval DR/DEA method. The efficiency scores provided by this method is different from one DMU to another, therefore they can be used to fully rank all the DMUs in interval DEA. This method is demonstrated through an example in the end. 