Endocrine multisystem defect polycystic ovary syndrome (PCOS) causes hyperandrogenism and infertility. Half of PCOS women have (non-alcoholic fatty liver disease) NAFLD, which increases metabolic disease risk. We tested decorin’s effect on NAFLD and related processes in PCOS. NAFLD+PCOS, PCOS+decorin, and control rats were studied. Decorin was evaluated on NAFLD/PCOS rats. Test group rats received HF for eight weeks to generate NAFLD. The rats got 1 mg/kg letrozole orally daily for 21 days to diagnosis PCOS. Afterward, rats got injectable decorin for 14 days. Body weight, liver weight, liver coefficient Abdominal Circumference (AC) and body mass index (BMI) were determined. Blood triglycerides (TG), total cholesterol, LDL-c, AST, and glucose were measured. The insulin, testosterone, estrogen, LH, and FSH were measured by ELISA. GPx, SOD, MDA, TNF- , and Caspase-3 liver immunohistochemistry were evaluated. NAFLD liver tissues in PCOS models showed biochemical and histological alterations. NAFLD+PCOS raised BMI, AC, liver weight, and coefficient. Blood glucose, insulin resistance, TG, ALT, and AST increased. Lipid abnormalities (TG, cholesterol, LDL-c, and HDL-c), oxidative stress markers (MDA, SOD, and GPx), and liver dysfunction were found. Low serum E2 and high T supported PCO. Decorin reduced model rat BMI, liver weight, coefficient, insulin resistance, TG, ALT, and AST. It reduced liver inflammation, improved liver extract lipids, and normalized MDA, SOD, and GPx. In the model