The researcher was conducted with a bank in Tehran, Iran, in 2009 and 2010 that aimed to determine the quality of services offered by Sepah Bank, and studied the relationship between the service quality, satisfaction and loyalty. This results of research show that in all five dimensions of service quality (Reliability, Responsiveness, Assurance, Empathy, Tangibles). In fact, findings of this research show that although in all five dimensions of service quality Sepah Bank’s performance has been higher than average limit,