The aim of this study is to develop a performance model for measuring relative efficiency and potential improvement capabilities of Nepali banks by scrutinizing intermediation aspects. For measuring the efficiency and performance, this paper uses a relatively new frontier approach known as Data Envelopment Analysis (DEA). The paper uses two basic DEA models to fulfill its objectives. This paper seeks to measure and analyze the efficiency levels of banks in Nepal during 2007-08 to 2010-11. The study reveals that efficiency level is relatively stable and has increased on overall. Additionally, it also breaks down the overall efficiency of banks into technical and scale efficiency. This study found no significant relationship with efficiency level and ownership structure of banks and there were no notable differences in the efficiency levels of banks according to their asset size.