This contribution addresses the following questions: Does unilateral sports-specific strain affect the skeletal system of the athlete? Specifically, can any differences be found in longitudinal growth of the bones of the forearm and hand in professional tennis players between the stroke arm and the contralateral arm? An investigation was conducted involving 20 high-ranking professional tennis players (12 male and eight female players) between 13 and 26 years of age as well as 12 controls of the same age range. The radiologic examinations of the bones of the forearm and hand yielded an increase in density of bone substance and bone diameter as well as length in the stroke arm as compared with the contralateral arm. Whereas the first results confirm previous findings, the stimulation of longitudinal growth has never been reported. This change in bone structure and size can be attributed to two factors: mechanical stimulation and hyperemia of the constantly strained extremity. It may thus be regarded as a biopositive adaptation process.