A Dissertation Submitted to the School of Business in Partial Fulfillment of the Requirement for the Award of the Degree of Master of Business Administration of Mzumbe University.Changes in the market in recent years have forced many businesses to focus on improving the quality of services in order to bring about customer satisfaction. This makes service quality be the central theme of many businesses s it ensures the attainment of customer expectations and positive perception of customers. This study aimed to assess the effect of customer expectation and perception towards service quality, using the case of NMB Bank in Dar es Salaam. The study-specific objectives included; to identify the role of empathy and assurance towards service quality, to assess how service tangibility and reliability affect service quality, to find out factor that influences customer expectation and perception on the service and to assess challenges that limits service provider to meet or exceed customer satisfaction. The study based on the case study design, held in two NMB branches, with a total sample size of 160 drawn through simple random and purposive sampling. Data collection techniques include questionnaires, observation, and interviews for primary data and document review for secondary data. Data were analyzed with multiple regression techniques and presented as well. From the finding, it was observed that most of the NMB customers tend to be satisfied with the existence of the tangibles, empathy, and responsiveness when receiving the service so the management should consider putting more emphasis on this so that to enhance the level of customer satisfaction. In conclusion, it has been revealed that NMB receives many customers due to the ability of the bank to meet the expectations of customers. Also, customers have a positive perception of the quality of services though there are still challenges that reduce the ability of the bank to meet the expectations of all its customers. Therefore, it is recommended that; the bank should work on improving their business from time to time because the banking industry is a competitive industry so customer reviews should be done from time to time so as to ensure the needs are well meet and customer expectation is met promptly and satisfied. Also, for further study in the banking industry other research should consider doing a paper on internet banking and using a bank service online as widely known as e-banking, it challenges impact, risks, and how they can satisfy customers.