This study examined the effect of mind mapping instructional strategy on students' retention in physics in senior secondary schools. The research is a quasi-experimental design of the pre-test, post-test, non-equivalent and non-randomized 2 X 2 X 3 factorial design. 64 students were sampled for this study out of which 28 formed the experimental group (mind mapping instructional strategy) while 36 of the respondents constituted the control group (conventional method). The pre-test and post-test contained 20 multiple-choice questions with four options one of which was the key factor while others were distractors. Multiple-choice questions were validated by three university professors. A retention test was also conducted after 2 weeks of the whole exercise. Data collected were analysed using the mean and standard deviation to answer the research question while hypotheses were tested using Analysis of Covariance (ANCOVA) and independent t-test at 0.05 significant level. Findings revealed among others that there was a significant effect of the mind mapping instructional strategy in physics in senior secondary schools It was therefore, recommended among others that mind mapping instructional strategy should be used to teach physics concept at the senior secondary school level of education for a better performance because it improves students' performances in physics.