© 2017This study aimed to determine whether there were any differences in trace element levels between adolescent boys with gynecomastia and control boys and to determine the correlations between the levels of trace elements and body mass index (BMI) and sex hormones. The pubertal gynecomastia group comprised of 41 patients (mean age = 13.2 ± 0.9 years), who were admitted to Hacettepe University İhsan Doğramacı Children's Hospital in Ankara. Control group comprised of 21 healthy male children. Analyses of trace element levels were performed atomic absorption spectrometry. The mean zinc level of control group was 101.33 ± 16.87 μg/dL and the mean zinc level of gynecomastia group was 81.36 ± 17,43 μg/dL (20% lower in gynecomastia patients, p = 0.0001). However, the mean copper and manganese levels of gynecomastia patients were not statistically different than the control group. There were significant positive correlations between plasma zinc and total testosterone levels in gynecomastia group (r = 0.592; p < 0.05). There was a significant negative correlation between plasma zinc levels and BMI (r = −0.311; p < 0.05). These results indicate that zinc deficiency might be one of the underlying factors of gynecomastia, the importance of which needs to be further elucidated.