Handboll, as a team-sport, puts emphasis on many different physical qualities where one is good jumping ability. The aim of this study was to examine if a small amount of additional plyometric training (PT) during in-season, combining drop jumps and box jumps could give significant improvements in vertical jump height in female handball players after five weeks of plyometric training. Jumping performance was evaluated through the squat jump test (SJ), countermovement jump test (CMJ) and a one-leg jump test (OLJ). The Intervention-group improved their jumping performance significant in all three tests. In contrast, the control- group had diminishing results in the SJ and CMJ but without any change in the OLJ. Furthermore, significant correlations were discovered between the SJ, CMJ and OLJ. The improvements seen in this study is relevant for coaches that need to provide gains in jumping performance during in-season when there is not a lot of time for additional training. The OLJ test developed in this study could be a first step to a future handball-test that better resembles the jumping performance in handball than already established two leg tests.