Energy, due to its increasing usage in various broad areas has been maintained as a vital factor in economic growth and development of societies. Meanwhile, natural gas is considered as one of the most important energy sources. Therefore, the efficiency and the productivity of the gas companies are crucial to be assessed. Numerous examples from industrial multistage processes including internal structures exist, such as petrochemical industry, perfume manufacturing, etc. Despite the fact that internal structures are not considered in conventional DEA, they are being taken into account in Network DEA. An evaluation of efficiency via Network DEA has been conducted in Iranian gas companies during 2002-2004 and the results are discussed in the following pages. After acquiring companies’ efficiency scores, we ranked them through Cross Efficiency (CE) technique thoroughly. Ultimately, we indicated the effectiveness of each input /output selected factors in efficiency measurement.