Introduction: Polycystic ovary syndrome is widely prevalent among adolescents and early diagnosis is crucial. While accurate diagnosis is not straightforward, anti-Mullerian hormone was found to be a reliable marker among young patients with polycystic ovary syndrome. However, its serum level was found to be affected by many other variables. This study assessed the relation between serum levels of anti-Mullerian hormone and body mass index in adolescents with polycystic ovary syndrome. Methods: This was a cross sectional analytical study, conducted at the Gynecology and Obstetrics outpatient clinics at Suez Canal University hospitals in Ismailia. It included 100 adolescents with PCOS who fulfilled the revised Rotterdam diagnostic criteria for PCOS, attending secondary stage or higher levels of education in Ismailia, Egypt. The recruited patients were divided into two groups. Group one reported to have BMI ≥ 30 and group two included those who have BMI < 30. Complete history taking, clinical examination (BMI) and biochemical markers including assessment of serum LH and AMH level, and ultrasound assessment to detect ovarian volume, antral follicular count, and presence of ovarian cysts. Results: AMH levels were not affected by BMI in adolescent patients with PCOS (r 0.19, p value 0.185). There were significant correlations between serum AMH and LH level, & between AMH and ovarian morphology among the studied population. The AMH was higher among those with menstrual irregularity and those with hyper-androginism. Accordingly, AMH level is not affected by patients' weight. Conclusion: The AMH was correlated to clinical and biochemical findings of PCOS.