Abstract : Martial arts are a sport that focuses on speed and individual strength to attack and avoid opponent attacks that require physical fitness. Optimal physical fitness is a factor that determines the performance of an athlete which is influenced by various factors including age, gender, exercise, genetics, and body composition (fat mass and body mass index). Previous studies have shown the relationship between fat mass and body mass index and fitness levels that have not been known to be associated with martial arts athletes. Martial arts athletes must adjust their weight to the class they are participating in so that sometimes the body mass index is above normal. This study aims to determine the relationship between fat mass and body mass index with fitness levels in martial arts athletes. A cross-sectional research design was carried out to see the relationship between fat mass and body mass index with fitness levels in martial arts athletes. The location of this research was conducted at a martial arts training center in West Java in April 2018 - September 2018. The results of the Pearson correlation test showed a negative correlation between fat mass and fitness (p = 0,000 and r = -0,729) and there was a negative correlation between body mass index. with fitness (p = 0.002 and r = -0.420). The greater the fat mass and body mass index, the lower the fitness level in martial arts athletes.