The main purpose of the research is to compare serum leptin (Lep) levels and adipose tissue percentage in adolescents diagnosed with polycystic ovary syndrome (PCOS) and those in healthy subjects. The results showed a greater percentage of patients with increased adipose tissue and significantly higher serum Lep levels in the PCOS group compared to the healthy controls. It was proved that there is a correlation between Lep and body mass index, body adipose tissue, waist circumference and HOMA index. PCOS in adolescents is a condition related to highly predominant overweight and obesity with exceeding level of body adipose tissue and higher serum Lep levels compared to healthy age-matched controls.