This study investigated simultaneous treatments in contextual interference (blocked and random practice) and their effect on the process of learning four tennis shots. 8 tennis players participated in the research, which was carried out in two phases. The first phase involved a 3-wk. period of 12 sessions with 192 practice tennis shots per session for each tennis player. The second phase comprised 4 retention tests carried out at 48 hr. and 2, 4, and 6 weeks following the learning phase. This phase consisted of evaluating the retention of the skills that had been practiced during the learning phase. The results indicated an improvement in the quality of shots for both practice conditions during the learning phase. Differences in retention appeared relative to differences in the type of practice conditions (random or blocked) in which the skill was learned and also depended on the type of shot and the time that had elapsed since the learning period.