The purpose of the study was to examine the relationships among aerobic fitness, anaerobic capacity, and performance indices of 2 different repeated sprint test (RST) protocols in a group of 33 elite adolescent soccer players (age range 16-18 years). All participants performed 4 tests: an aerobic power test (20-m shuttle run), the Wingate Anaerobic Test (WAnT), and 2 different RST protocols (12 x 20 and 6 x 40 m). Significant correlations (p < 0.05) were found between the fastest sprint (r = 0.618), total sprint time (r = 0.709), and performance decrement (PD; r = 0.411) of the 2 RST protocols. A significant negative correlation was found between the PD in the 12 x 20-m RST and calculated peak VO2(r = -0.60, p < 0.05). There was no significant correlation between PD of the 6 x 40-m RST and calculated peak VO2(r = -0.32, p = 0.09). The mean power in the WAnT was significantly correlated with the fastest sprint and the total sprint time of the 6 x 40-m protocol (r = -0.42 and -0.45, respectively) and with the total sprint time of the 12 x 20-m protocol (r = -0.47). There were no correlations between other indices of the WAnT and the 2 RSTs. Despite identical total work, different RST protocols represent different physiological implications. The aerobic system plays a significant role in the maintenance of intensity level during a soccer game, which is characterized by short bursts of activities. Anaerobic performance of repeated brief efforts imposes different physiological stress than a single prolonged activity and, thus, may reflect different physiological capabilities. Therefore, anaerobic testing procedures should consist of specific protocols that mimic the athlete's specific sports activity pattern.