This paper investigates and clarifies the concept of fairness in the secondary use of health data for scientific research purposes, particularly within the context of the European Health Data Space (EHDS). By conducting a comprehensive scoping review of argument-based literature, this research seeks to shed light on the multifaceted nature of fairness in this domain. Through an inductive approach and thematic analysis, the paper identifies key elements of fairness, such as balancing individual and public interests, mitigating power imbalances, defining conditions for commercial involvement, and promoting benefit sharing. Ultimately, the paper aims to provide valuable insights that can inform current and future research practices and policy development, helping to ensure that the secondary use of health data is conducted ethically and fairly while maximizing its contributions to scientific research and healthcare enhancement.