The goal of this study was to find out the effective diet prescription for the exercises. To accomplish this purpose, we investigated the effect of free-fatty acid diet (FFAD) on two groups of the K technical high school soccer players; one group with 7 members for normal diet (NORD) and another group with 7 members for high-fat diet (HFD). HFD group was fed far three days before the game. Results were as follows: i) Blood glucose level was increased with statistical significance in HFD group (P<.01) compared to the NORD group. After plying game, the glucose level was increased in the both groups ii) The contents of free-fatty acid (FFA) was significantly increased in HFD group (P<.0001) compared to the NORD group. After playing game, the FFA level was also increased in both groups iii) The levels of T-C, HDL-C and LDL-C were slightly increased in both NORD and HFD groups after playing game, while the TG level was slightly decreased. However, the differences were not significant. These results imply that HFD may not affect the level of seam lipids. Overall, the level of glucose and FFA were increased, but other types of lpids were not changed. From these studies, we observed the increase in the level of glucose and FFA but not other sew lipid. These results indicate that HFD may induce the body energy-utilizing system during long-lasting exercise such as playing soccer game.