Aim. In spite of the increasing scientific interest in the epidemiology of overweight and obesity in children and adolescents, less attention was paid to the prevalence of these disorders in sport setting. The aim of this study was to investigate the prevalence of overweight and obesity in adolescent soccer players. Methods. Male adolescent (N.=297 aged 12.01-20.98 y), classified in nine one-year age-groups, children (control group, N.=16 aged 7.34-11.97 y) and adult players (control group, N.=29 aged 21.01-31.59 y), all members of competitive soccer clubs, performed a series of anthropometric measures (body mass, height, skinfolds and circumferences), from which body mass index (BMI), percentage of fat (BF), fat mass (FM), fat free mass (FFM) and waist-to-hip ratio (WHR) were calculated. Results. After having partitioned out the effect of age on the parameters of body composition, BMI was associated moderately to strongly with BF, FM and FFM (r=0.74, r=0.88 and r=0.68, P<0.001), while there was no corresponding relationship between WHR and BF (r=0.03, P=0.64). The prevalence of overweight/obese ranged 13.3-32.4%. Although there was no difference between adolescent age groups, the difference between adult and child control group (chi(2)=7.09, P<0.05; higher prevalence in children than in adults) indicated an attenuation of this prevalence with development. Conclusion. Based on these findings, the prevalence of overweight/obesity in adolescence was confirmed. However, what was novel was that this phenomenon was identified in adolescent sport setting and, consequently, exercise interventions with proper mode, duration and intensity, targeting this phenomenon, should be applied by coaches and fitness trainers.