Background: The aim of the present study was to examine the effect of one or two changes of direction (COD) on performance indices in a 10x15 m repeated sprint ability exercise (RSA) in 9-year-old basketball players. Fourteen basketball players (age 9.4 ± 1.7 yrs, height 142 ± 13 cm and weight 39 ± 10 kg) performed an RSA protocol in three different conditions on a counterbalanced order on separate days: (A) in straight line (RSASL), (B) with one COD (RSACOD, i.e., 10 × (7.5 + 7.5 m)) and, (C) with two COD (RSA2COD, i.e., 10 × (5 + 5 + 5 m)). Sprints started every 30 s (passive recovery); time variables were total time (TT), best time (BT) and fatigue index (FI). Countermovement jump (CMJ) was tested before and after each RSA protocol. Heart rate (HR) was continuously monitored during testing procedures. RSASL, RSACOD and RSA2COD differed for TT (p<0.001, η 2=0.98), BT (p<0.001, η2=0.98), with faster times in RSASL, and FI (higher value in RSA2COD; p=0.001, η2=0.67). A repeated measure 2 × 2 ANOVA showed a main effect of RSA on CMJ (increase; p=0.019, η2=0.34), whereas there was not main effect of RSA format (p=0.061, η2=0.19) nor interaction (p=0.945, η2<0.01). No difference was observed in HRmean (p=0.340, η2=0.30) and HRpeak (p=0.418, η2=0.25). These findings showed that performing repeated sprints with two COD resulted in increased fatigue compared to RSA in-line or with one COD in 9-year-old basketball players.