Logistic service provider or express delivery as the specialty of CV ZC Fast requires a good service quality in maintaining customer satisfaction due to the increasing demand of the users. The objective of this research is to know whether there is the influence of service quality on customer satisfaction at CV ZC Fast in Medan. The methods used by the writer in this research are descriptive method and correlation method. Population in this research is 162 customers of CV. ZC Fast and sample in this research is 115 employees with used the Slovin formula. Technique of data analysis is by using Linear Regression Analysis, Coefficient Determination and Z test. From the results of research to the company, the Z test, it can be seen that Zcount (7.74) is higher than Ztable (1.96). From the correlation test, the correlation value is 0.725. This means that there is a strong and positive relationship between service quality and customer satisfaction at CV ZC Fast in Medan. The coefficient of determination is 52.5%. That is, 52.5% change in customer satisfaction can be explained by service quality. The linear regression equation is Y = 2.264 + 0.893 X. This means that an increase of 1 unit of one unit service quality will improve customer satisfaction by 0.893 units. Conclusion of this research is that service quality has impact on customer satisfaction at CV ZC Fast in Medan.