Elite athletic endurance ability involves multiple genetic and environmental factors, with little known about the specific genotypes involved. As a first step to finding genetic markers of endurance performance, we recruited 66 male endurance runners and 110 control athletes. We investigated the distribution of m.5178CA polymorphisms in male endurance runners. Although the m.5178A genotype has been reportedly associated with longevity, endurance runners in this study showed a significantly higher frequency (71.2%) of the m.5178C genotype than control subjects (52.7%). The-m.5178C genotype may be favorable for performance in elite endurance runners.