This study was intended to analyze the relative rate of contribution of physical structure and motor ability sub-domains contributing to swimming performance of competitive college male swimmers. Subjects were 75 highly trained college male swimmers. Fourty-three variables were selected according to hypothetical structure of physical condition for swimming performance. Factor analysis applied to the 43×43 correlation matrix has yielded 12 sub-domains of physical condition. Multiple regression analysis was then applied to swimming performance score and scores for various sub-domains to determine the relative degree of contribution of each physical condition sub-domain to the swimming performance. The results were as follows : 1. The physical condition sub-domains for top college male swimmers were represented by the following 12 factors : 1) body bulk, 2) fundamental swimming ability, 3) leg strength; 4) posture, 5) ankle flexibility, 6) arm strength, 7) body linearity, 8) endurance, 9) general flexibility, 10) trunk flexion, 11) agility and 12) coordination. 2. The best swimming record in 1982 for each subject was then standardized with the mean and standard deviation computed from official records of 1980-1982 Intercollegiate Swimming Championship Meets. These values were considered appropriate as the measure of individual's swimming performance since coefficients of variation for various swimming events and their relative speeds to the respective world record remained essentially constant. 3. Analysis of the data indicated that 4 sub-domains of physical condition, i.e., fundamental swimming ability (35.0%), coordination (26.5%),leg strength (15.9%), and posture (10.6%) had markedly higher relative rate of contribution to swimming performance. From these results, it is suggested that fundamental swimming ability (e.g., strokes in 25m swimming) and coordination (e.g., rhythm and timing control) are of great importance in producing highly trained college male swimmers. Training for muscle strength particularly on legs is also emphasized. Specific training for improving abilities in these sub-domains is recommended to add to the regular training. It should be noted that some of excellent swimmers were characterized by straightened spine curvature.