Twenty eight stress tests for 14 wheelchair marathon competitors were performed to determine their physical fitness just before the Oita International wheelchair marathon since 1984. All the subjects were wheelchair-bound Japanese males and workers at Sun Industry. Oxygen consumption at the maximal workload was significantly larger than that of non-athletic paraplegics and the mean values were 35.0 +/- 4.8 ml/kg in competitors and 22.6 +/- 5.0 ml/min/kg in non-athletic paraplegics. Eight competitors had more than 2 stress tests and 6 of them had 3 tests from 1984 to 1987. The oxygen consumption at the maximal workload of their third test was very high (46.5 +/- 6.8 ml/min/kg) equal to highly trained paraplegics, and was larger than the result of the first test significantly. Their physical fitness was reduced significantly during the off season, however their physical fitness was maintained at a satisfactory higher level than that of non-athletes. This study demonstrated that individual training for wheelchair marathoners had improved the competitors' physical fitness over several years.