The purpose of this study was to determine whether gender- and age-related differences in ankle joint complex (AJC) range of motion (ROM) exist in children (range 9-13 years), adolescents (14-16 years), and young adults (17-20 years), and to compare these data with those published for older subjects (21-79 years) using the same protocol. A total of 120 subjects (58 males and 62 females) ranging in age from 9 to 20 years were tested for AJC ROM using a specifically designed 6 degrees of freedom fixture. All measurements were made with respect to a laboratory coordinate system, and represented assessment of active AJC ROM. Angular displacements for plantarflexion, dorsiflexion, inversion, eversion, abduction, and adduction were digitally recorded and compared. AJC ROMs of females aged 9 to 20 years were generally greater than those for males about all three orthogonal axes. Within each gender, there was a consistent trend for AJC ROM to decrease from a maximum at 14 to 16 or 17 to 20 years to a minimum after age 60 years. The average decrement was greater for females than for males. This study provided evidence to support the contention that age-related and gender differences in AJC ROM do exist. The possibility of minimizing the decline in AJC ROM with age requires further investigation.