['The specific aim of the study was to investigate and compare epiphyseal length and extension in the proximal humerus, closure in the growth plate and bone marrow signal intensity related to the proximal humeral physis in the dominant arm and the non-dominant arm of the asymptomatic adolescent elite tennis player.', 'The study sample included 35 asymptomatic elite young tennis players (15 males and 20 females, mean age 17.4\xa0years\xa0±\xa02.7). Each player contributed with two shoulders to the MRI measurement. The non-dominant arm was used as a control.', 'Relative reliability between the radiologists was excellent (ICC 0.78-0.96). Statistically significant differences between dominant arm and non-dominant arm in epiphyseal length (mm) laterally (DA 27.3 vs NDA 26.7) were shown. Statistically significant differences were also found in epiphyseal extension (mm) laterally (DA 36.1 vs NDA 35.1) and ventrally (DA 36.2 vs NDA 34.8). No statistically significant differences were found between dominant arm and non-dominant arm in epiphyseal extension (mm) medially (DA 31.7 vs NDA 31.7) and dorsally (DA 22.6 vs NDA 22.1).'] Do asymptomatic elite young tennis players show lateral and ventral growth plate alterations of proximal humerus on MRI?