This study examined the effect of six weeks of progressed and non-progressed volume-based overload plyometric training (PT) on components of physical fitness and body composition measures in young male basketball players, compared with an active control group. Participants were randomly assigned to a progressed PT (PPT, n=7; age=14.6±1.1 years), a non-progressed PT (NPPT, n=8, age=13.8±2.0 years), or a control group (CG, n=7, age=14.0±2.0 years). Before and after training, body composition measures (muscle-mass, fat-mass), countermovement-jump with (CMJA) and without arms (CMJ), horizontal bilateral (HCMJ) and unilateral jump with right (RJ) and left (LJ) legs, 20-cm drop-jump (DJ20), sprint speed (10 m sprint), and change-of-direction speed (CODS [i.e., T-test]) were tested. Results: Significant effects of time were observed for muscle- and fat-mass, all jump measures, and CODS (all p<0.01; d=0.37-0.83). Significant training-group×time interactions were observed for all jump measures (all p<0.05; d=0.24-0.41). Post-hoc analyses revealed significant pre-post performance improvements for the PPT (RJ and LJ: ∆18.6%, d=0.8 and ∆22.7%, d=0.9, respectively; HCMJ: ∆16.4%, d=0.8; CMJ: ∆22.4%, d=0.7; CMJA: ∆23.3%, d=0.7; DJ20: ∆39.7%, d=1.1) and for the NPPT group (LJ: ∆14.1%, d=0.4; DJ20: ∆32.9%, d=0.8) with greater changes after PPT compared to NPPT for all jump measures (all p<0.05; d=0.21-0.81). The training efficiency was greater (p<0.05; d=0.22) after PPT (0.015% per-jump) compared to NPPT (0.0053% per-jump). The PPT induced larger performance improvements on measures of physical fitness as compared to NPPT. Therefore, in-season progressive volume-based overload PT in young male basketball players is recommended.