The purpose of the present study is to determine whether athletic characteristics can be discriminated by changes in serum components during exercise which are considered to reflect systemic endurance capacity, muscle strength, and the energy metabolism system. Thirteen male long-distance athletes and 8 male short-distance and field athletes performed an incremental exercise test, muscle strength, and endurance test. They were also observed for changes in serum components during exercise. According to data analysis, the discriminant function thus obtained was: Z=0.8220×peakVO2+0.0037×AT+0.0010×MVC+(-0.0276)×60deg/sec+0.2629×MVC500me+(-0.8715)×UN+36.1659(peakVO2: measured value of peak VO2, AT: 0xbfffa670eakVO2, MVC: measured value of the isometric muscle strength, 60deg/sec: peak torque of the isokinetic muscle contraction at 60deg/sec, MVC50-1230722560me: the time for the previously determined isometric muscle strength value to become less than 50%, UN: the increase rate of UN from the value at rest to the maximum value). Subjects were classified into the actual group correctly, while the erroneous discriminant rate was 0.73%.0 In particular, weighting of the discriminant coefficient of peakVO2 and UN was large, indicating that these are useful as parameters for discriminating athletic characteristics.