Service quality plays an important role in service industries such as banks, insurance firms, etc. The purpose of this paper is to investigate level of service quality in private banking industry in Iran. The proposed model of this paper uses SERVQUAL tool for measuring service quality and population of this study includes customers of three private banks in Tehran. Results show that except efficiency, other variables of SERVQUAL obtained suitable level mean in this study. As a result, with the development of electronic commerce, internet banking has become an alternative for developing, operating and offering bank services.