Physical and anthropometric characteristics have been associated with differences between levels of swimming performance, swimming events, training status, gender, and age. It has been suggested that the greater body fatness observed in girl swimmers than boy swimmers could explain the gender differences in performance. Few studies, however, have examined gender differences in the physical and anthropometric characteristics of young swimmers. The purpose of this study was to compare the body composition, body build, and anthropometric characteristics of boy and girl sprint swimmers. Two groups (boys, n = 38 and girls, n = 31) of sprint swimmers (mean age ± SD = 11.03 ± 2.29 and 10.45 ± 2.29, years, respectively) volunteered for this study. The subjects were members of local swimming clubs who competed in sprint swimming events (≤ 200 m). Gender comparisons were made for age, body weight (BW), height (HT), fat-free weight (FFW), percent body fat (%fat), endomorphic rating, mesomorphic rating, ectomorphic rating, sum of 12 diameters, sum of 11circumferences, biacromial diameter/biiliac diameter, and FFW/HT. The results of the independent t-tests indicated that the only mean differences between the boy and girl sprint swimmers were for % fat (boys = 9.40 ± 5.35 % fat; girls = 12.73 ± 6.19 % fat) and endomorphic rating (boys = 2.87 ± 0.96; girls = 4.29 ± 1.22). For the current age group of sprint swimmers, the only gender differences were for measures associated with body fatness and there were no differences for body build measures associated with musculoskeletal size, muscularity, skeletal size, total body mass, or body breadth dimensions. Further studies are needed to examine gender differences in the body composition and body build of distance swimmers, older sprint and distance swimmers, and athletes in sports other than swimming. These findings suggest that gender differences in sprint swimming performance may be reduced through training programs for girls designed to reduce body fatness.