This study aims to analyze the influence of service quality on satisfaction and loyalty of BRI customers, especially at the BRI Wonosari branch office. This research is an explanatory study with the population of this study are BRI customers in Wonosari who have been customers for at least one year and minimum transactions is 12 times a year. This study uses purposive samples with a sample of 140 samples. Data analysis with Path Analysis, namely by partial statistical test (t test), coefficient of determination. The results obtained from the study namely Service Quality Perception have a positive and significant effect on Bank Customer Loyalty with a result of 0,000 with a positive T count of 3,918 and a positive regression coefficient of 0,250. Because the significant value obtained is <0.05 and the regression coefficient is positive, Ho is rejected and it is concluded that the perception of service quality has a positive and significant effect on bank customer loyalty: Perception of Service Quality has a positive and significant effect on Bank Customer Satisfaction with a yield of 0,000 with T count positive is 8.819 and the regression coefficient is positive as 0.600. Because the significant value obtained is <0.05 and the regression coefficient is positive, Ho is rejected. Customer Satisfaction has a positive and significant effect on Bank Customer Loyalty with a result of 0,000 with a positive T count of 9.7797 and a positive regression coefficient of 0.626. Because the significant value obtained is <0.05 and the regression coefficient is positive, Ho is rejected. Customer Satisfaction the bank can mediate the indirect influence of perceived quality of service variables on customer loyalty with the results of the Sobel test obtained a significant value of the test results of 0,000. Because the significant value obtained is <0.05, Ho is rejected and it is concluded that the variable customer satisfaction can significantly mediate the indirect effect of perceived quality of service variables on bank customer loyalty.