Background: Polycystic ovary syndrome (PCOS) diagnosis is controversial in adolescents. Therefore, auxiliary markers are required for the diagnosis of PCOS. Aim and Objective: We aimed to evaluate whether luteinizing hormone (LH)/ follicle-stimulating hormone (FSH) ratio, free androgen index (FAI), anti-Mullerian hormone (AMH), and sex hormone-binding globulin (SHBG) levels are a useful test to screen adolescents with PCOS and to investigate which of them has more diagnostic value in the PCOS diagnosis. Material and Methods: A total of 28 girls with PCOS and 35 healthy girls consisted in this study. Pediatric Endocrine Society criteria were used to diagnose PCOS. Clinical examinations and hormonal assays were performed. Results: The LH/FSH ratio, and FAI levels were detected significantly higher, and SHBG levels were detected significantly lower in the PCOS group than in the control group (p<0.001). The best marker for PCOS diagnosis was found as AMH. In all adolescents with PCOS, irrespective of obesity/overweight, significantly higher AMH levels were observed compared to the control subjects (p<0.001). Also, we measured a LH/FSH ratio cut-off value of 1.48 ng/ml with 77% sensitivity and 77% specificity to differentiate cases with PCOS from healthy controls. Conclusion: AMH, FAI, and LH/FSH ratio could be useful and valuable tests for the PCOS diagnosis in the presence of the PCOS criteria. AMH was found to be the strongest diagnostic marker in patients with PCOS.