This study was to investigate the effects of 8-week overseas winter training for skill improvement on body composition, blood profile, physical fitness, and golf performance as an overtraining markers. The participants were composed of male high school golfers(n=10) with official handicap 3.20±0.61. As a result, body composition, muscular strength, and flexibility were significantly decreased after overseas winter training. The significant weight loss was observed before with all other occasion. Between 0-2week and 2-4week showed significant decrease in weight and dietary intake. The maximal oxygen uptake and golf drive distance have shown to a tendency to decrease, but not significant. There was significant decrease in cortisol level after winter training. In conclusion, high school golfers attending an overseas winter training camp showed several overtraining markers which may lead to the generation of overtraining state, the decrease of golf performance and the increase of sports injury. Therefore, planned training include conditioning according to the golfers' condition and the circumferences should developed.