This research study investigated the effect of concentrations of “Gari" solution on endurance ability of school children in Ilorin metropolis, Nigeria. The design of the study was experimental that involves the manipulation of a particular variable. In order to provide solution to the research problem, four hypotheses were drawn. Forty[40] subjects were randomly selected as sample from four male secondary schools in Ilorin metropolis and they are those that are not actively involved in sports, but within the age limit of 12-13 years. Standardized instruments were used for both the experimental and control groups. The results of the experimental groups showed a significant difference on the effect of concentrations of “gari" solution on endurance ability of school children in Ilorin metropolis within 6%, 7%, and 8% respectively. The three groups with treatment improved tremendously on their performance over the result of the post-test and that of the control group. This showed that each percentage of the treatment has improved the performances ability of the school children in endurance activities of 4km run/walk. Based on the finding, it was recommended among others that, coaches, athletes and others involved in endurance activities should cultivate habit of taking “gari" solution to enhance their performances.