Objectives: Compare clinical and metabolic parameters, as well as predictors of metabolic syndrome (MS), in adolescent and adult women with polycystic ovary syndrome (PCOS). Methods: A Cross-sectional study was conduced in Faculty of Medicine of Ribeirao Preto, University of Sao Paulo. A total of 147 women with PCOS were divided into 2 groups: 42 adolescents and 105 adults. Anthropometric measurements, blood samples and pelvic ultrasound exams were made to assessment of the prevalence of MS and its components. Furthermore, the predictors of MS in women with PCOS were evaluated by multivariate analysis. Results: The prevalence of increased diastolic blood pressure and changes in the lipid panel was greater in adult women than in adolescents (p<0.02). The prevalence of MS was greater in adult women than in adolescents (49.5% vs. 23.8%, p=0.01). In adult women, insulin levels and body mass index (BMI) were independent predictors of MS incidence (p<0.01), but in adolescents, only BMI was found to be an independent predictor of MS (p<0.03). Conclusions: The insulin levels and BMI were independent predictors of MS in the adult women with PCOS, however, for adolescents, only the BMI was independent predicted of MS, emphasizing the need to monitor these patients from adolescence to prevent metabolic complications.