Customers evaluate a product or service in terms of whether that product or service has met rntheir needs and expectations. Customer satisfaction is derived largely from the quality and rnreliability of products and services. Commercial banks encounter similar problems in meeting rncustomer’s expectation of services and customer satisfaction. The general purpose of this paper rnwas to assess the effect of service quality on customer satisfaction in Wegagen Bank S.C. The rnsample was 136 customers from five branches of Wegagen Bank Share Company operating in rnAddis Ababa city. Convenience sampling was used to select a sample. Data was collected using rnquestionnaires and analyzed and presented using descriptive as well as inferential statistical rntools including the use of frequency, tables and Pearson Correlation Coefficient and linearrnregressions with the help of Statistical Package for Social Sciences (SPSS) version 20. Research rnfindings revealed that most of the customers who use Wegagen bank services are satisfied or find rnthese services 'average'. The responsiveness and assurance dimensions of service quality found rnto be the significant contributors customer satisfaction. The determinant factors; responsiveness rnfor customer’s need and assurance of the bank have been found to have a statistically positive rneffect on customer satisfaction hence there is need for Wegagen bank to improve on these rndeterminant factors.