The present study compared the effects of two repeated-sprint training (RST) programs, differing in duration of the between-sprint rest intervals, on various soccer-related exercise performances. For 5 weeks during the competitive season, twenty-nine young trained male soccer players either replaced two of their habitual fitness conditioning sessions with RST characterized by short (5-15; n = 9) or long (5-30; n = 10) rest intervals, or served as control (n = 10). The 5-15 and 5-30 protocols consisted of 6 repetitions of 30-m (∼5 s) straight-line sprints interspersed with 15 s or 30 s of passive recovery, respectively. 5-15 improved 200-m sprint time (2.0±1.5%; p<0.05) and had a likely positive impact on 20-m sprint performance, whereas 5-30 lowered the 20-m sprint time (2.7±1.6%; p<0.05) but was only possibly effective for enhancing the 200-m sprint performance. The distance covered during the Yo-Yo Intermittent Recovery Test Level 2 increased following 5-15 (11.4±5.0%; p<0.05), which was possibly better than the non-significant 6.5% enhancement observed in 5-30. Improvements in the total time of a repeated-sprint ability test were possibly greater following 5-30 (3.6±0.9%; p<0.05) compared to 5-15 (2.6±1.1%; p<0.05). Both RST interventions led to similar beneficial (p<0.05) reductions in the percentage decrement score (∼30%) of the repeated-sprint ability test as well as in blood lactate concentration during submaximal exercise (17±18%). No changes occurred in the control group. In soccer players, RST over a 5-week in-season period is an efficient means to simultaneously develop different components of fitness relevant to match performance, with different benefits induced by shorter compared to longer rest intervals.