This study aims to examine the relative efficiency of 19 Thai commercial banks during 2006 to 2010 by utilizing Data Envelopment Analysis (DEA) via operation approach and intermediation approach. The analysis conducted with the 19 commercial banks in Thailand from 2006 until 2010. The data source of this study is Bureau Van DIJK’s Bank Scope database. The banks’ unconsolidated statements are utilized if available. Regarding the Database, the evaluation covers 17 local Thai commercial and retail and 2 foreign banks with a full branch (one location) in Bangkok. The main findings in term of size, large banks are superior over medium and small banks via operation approach probably due to their economies of scales, while small banks are the most efficient ones under intermediation approach since they possibly to have a comparative advantage in providing lending relationship to small borrowers and offer less criteria for loan approval. In term of ownership status, foreign-owned banks perform the best role as financial intermediaries via intermediation approach seemingly owning to their reputation among financial institutions and their higher loan interest rate. State owned banks are inferior to private domestic and foreign banks since they appear to have lower net interest rate but higher NPL and overhead cost.
