The aim of this study was to identify the effect of using arms in Vertical Jump test on the Reactive Strength Index (RSI) of basketball players and its relationship to sprints (speed 20m) and change of direction (T- test) performance. The study sample consisted of 20 Basketball players of junior youth, (age: 14.25±1.59 years), (body mass: 58.28±15.41 Kg), (height: 170.60±11.32 m) and (body mass Index: 19.73±3.72 Kg/m2 ) from Oman Basketball Association Clubs. Participants performed the following Jump tests: Countermovement Jump (CMJ), Free Countermovement Jump (FCMJ), Drop Jump (DJ) and Free Drop Jump (FDJ). The RSI has been calculated by dividing the flight time by the take-off time during tests of: CMJ (RSICMJ), (RSIFCMJ) and DJ (RSIDJ), (RSIFDJ). They also performed T-test and Speed 20m test. The results demonstrated the effect of using arms on the (RSI) calculated from CMJ test (p=0.038, 0.26±0.52, 0.14±0.46), and DJ test (p=0.0009, 0.24±0.78, 0.26±0.68). Also, the results demonstrated a significant positive correlation between the RSICMJ and RSIFCMJ (p≤0.01, r=0.554), and also between RSIDJ and RSIFDJ (p≤0.01, r=0.81). There was no significant correlation between RSI calculated from all jump tests on the one hand and T-test & Speed 20m test on the other hand. These results indicate that using arms affects calculating the RSI through CMJ and DJ tests. In addition, the RSICMJ and RSIFCMJ are considered independent variables that evaluate different capabilities, on the contrary of RSIDJ and RSIFDJ. These results are very important to the coach and the physical trainer in terms of evaluating muscle's ability and designing the appropriate plyometric programs to develop the muscle's ability.