The aim of this study was to compare the effectiveness of cognitive strategies based on mental imagery at different speeds (slow, real, and fast) on improving volleyball serve performance. 48 subjects with an age range of 19 to 23 years were selected conveniently and were divided into four groups of imagery at slow, real, fast, and control speeds based on the results of the pre-test. After initial volleyball serve skill training, subjects performed the skill during 9 practice sessions. In addition to receiving instructor instructions, the experimental groups used mental imagery appropriate to their group, while the control group only performed physical training. The subjects' performance was assessed in the pre-test, post-test, and retention stages. Data were analyzed using composite analysis of variance, one-way analysis of variance, and Tukey's post-test. The results showed that in the acquisition phase, the main effect of stage was significant and all groups improved their performance in the post-test compared to the pre-test, but no significant difference was observed between the groups. In the retention phase, there was a significant difference between the groups; so that the imagery group with the real rhythm showed better performance than the control group. Despite the superiority of the mean of the fast and slow imagery groups over the control, these differences were not significant. Also, no significant difference was observed between the three imagery groups. The findings indicate that mental imagery, especially with the real rhythm, can be more effective in consolidating and retaining volleyball service skills