The purpose of this study was to ascertain whether exercise training cardiac adaptation exists in student rugby athletes, to define an adaptive pattern and to observe the student rugby athletics cardiac adaptive process. Subjects consisted of 42 male senior high school student rugby athletes, who participated in sports in junior high school, and a control group of sedentary students from the same senior high school who were matched for age. Student athletes were measured once a year over a three-year period. Left ventricular internal dimension at the end-diastole (LVIDd) and left ventricular posterior wall thickness at the end-diastole (PWT) were both measured by echocardiography. Because all subjects were growing adolescents, allometric scaling data (which is LVIDd/BSA^0.5 and PWT/BSA^0.5) was used for comparison, to preclude the effect of differences in body size on LVIDd and PWT. Cross-sectional comparisons of athletic students with controls were conducted for each of the three senior high school grades, respectively. The data of student athletes during the three-year study was used for longitudinal comparisons. The results of cross-sectional comparisons showed that LVIDd/BSA^{0, 5} in a student athlete group consisting of the three grades combined was greater than the corresponding control group (P<0.05, P<0.01, respectively) . PWT/BSA^0.5 in the athletic group was greater than the control group for the third grade level (P<0.05) . The results of the longitudinal comparison revealed that no significant differences were present in LVIDd/BSA^0.5 during the three-year investigation (P>0.05, respectively) . PWT/BSA^0.5 at the second and third grade level were obviously greater than at the first grade level (P<0.05, respectively) ; however, no dif. ference between the second and third grade levels existed. The results of this present study suggest that regular rugby exercise training during senior high school obviously induced left ventricular posterior wall thickening in the athletic students. An enlarged left ventricular cavity was observed at the first grade level of senior high school and did not significantly change during three years of senior high school.