Polycystic ovary syndrome (PCOS) is a complex endocrine disorder associated with metabolic dysfunction. This study investigated serum endotrophin levels, a novel adipokine, in PCOS patients and its relationship with metabolic parameters. In this case- control study, 40 women with PCOS and 40 healthy controls were enrolled. Serum endotrophin levels, metabolic parameters and anthropometric measurements were assessed. Women with PCOS had significantly higher serum endotrophin levels compared to controls (7.1 + 5.6 ng/mL vs 1.9 + 1.7 ng/mL, p < 0.0001). Endotrophin levels were positively correlated with BMI (r = 0.4120, p = 0.0001), waist- to-hip ratio (r = 0.3857, p = 0.0004) and blood pressure (SBP: r = 0.3275, p = 0.0030; DBP: r = 0.4076, p = 0.0002). No significant correlations were observed between endotrophin and fasting glucose, insulin, or HOMA-IR. ROC curve analysis revealed high diagnostic accuracy of endotrophin for PCOS (AUC = 0.9641, sensitivity 95%, specificity 90%). These findings demonstrated that serum endotrophin levels are elevated in PCOS and correlate with key anthropometric measures, suggesting its potential role in PCOS pathogenesis. The high diagnostic accuracy indicates endotrophin's as a novel biomarker for PCOS. Further metabolomic research could reveal the mechanistic links between endotrophin and PCOS pathophysiology.