This research aimed to investigate the effect of service quality on customer loyalty in sports-fitness facilities. The sample of the research consisted of 311 individuals, 165 males and 146 females, who were members of 6 sports – fitness centers in Istanbul and Niğde. In the research, a questionnaire containing 3 parts was used as a data collection tool. In the first part, the items defining the research group were included. In the second part, "Scale of Perceived Service Quality of Sports-Fitness Centers" developed by Uçan (2007) was used. In the third part, the "Customer Loyalty Scale" developed by Zeithaml et al., (1996) and adapted into Turkish by Savaş (2012) was used. SPSS 22 program was used in the analysis of the data, while detailed graphic statistics were used for demographic data, scale scores, and regression analysis was used for relational analysis. When the descriptive statistics results of the research were examined, it was observed that the perceived service quality sub-dimension scores and customer loyalty scale scores were above the mean. Looking at the relational analysis part of the research, it was determined that interaction, output and program quality in sports-fitness facilities had a significant positive effect on customer loyalty. According to these results, it was suggested that sports facilities should give importance to interaction, output and program quality to ensure customer loyalty.