Objective: The aim of the present study was to identify the factors influencing customer complaint behavior in the sports services industry.Methodology: The research employed a qualitative method with a thematic analysis approach based on Braun and Clarke (2006). The study's population included experts in sports marketing with a focus on customer orientation, managers of health and wellness clubs, swimming pools, and customers who use these services. A purposive sampling method was used, involving 27 participants. The research tools included a systematic literature review and semi-structured exploratory interviews, whose validity and reliability were confirmed.Results: According to the research results, the factors influencing customer complaint behavior in the sports services industry include 87 concepts, 8 subcategories, and 3 main categories: customer-related elements (customer behaviors, purchase-related behaviors, and customer perceptions); internal organizational elements (organizational performance, staff performance, and inadequate service delivery); and external elements (economic and socio-cultural factors).Conclusion: Sports organizations can prevent customer dissatisfaction by improving the quality of sports services and identifying customer expectations, perceptions, and behaviors in using these services. By establishing a high-quality complaint management system with clear mechanisms and accessible complaint channels, alongside training and empowering staff, organizations can promptly address customer issues. Moreover, by implementing processes and procedures that align with customer perspectives and responding to complaints with respect and attention, organizations can increase customer retention rates and contribute to improving their profitability.