Fitness tests have become essential tools used by sports scientists and fitness coaches in recent years to evaluate the physical abilities and health status of athletes. Measurement and evaluation of aerobic capacity comes to the fore in determining the physical fitness level. Tests that measure aerobic endurance are classified according to how they are applied, such as the duration and intensity of the load. In addition to tests performed with continuous loads such as the Cooper Test and the 20 m Shuttle Run Test, tests performed with intermittent loads are also frequently used. The two most prominent tests developed to estimate an individual's capacity to do intermittent exercise are the Yo-Yo Intermittent Recovery Test and the 30-15 Interval Fitness Test. The Yo-Yo IR1 test, which lasts 10 to 20 minutes, primarily evaluates the endurance capacity of trained individuals, while the 30-15 Interval Fitness Test, which has a similar purpose, is used in football, basketball, netball, etc. as in Yo-Yo tests. It is a test designed to determine aerobic capacity by providing the opportunity to rest in a way similar to the intermittent structure in sports branches. These two tests, which have many similarities with each other, can differ in terms of their advantages and disadvantages. The purpose of this study is to reveal the similarities and differences between these two tests.