Abstract Disclosure: S. Rodriguez Ortega: None. I.R. Bass: None. Background: Increased adiposity enhances the phenotypic expression and severity of hyperandrogenism in women with Polycystic Ovarian Syndrome (PCOS). Weight loss has been associated with improved endocrine features in women with PCOS and elevated Body Mass Index (BMI). Bariatric surgery can be an effective means of significant weight loss and restoration of the hypothalamic pituitary axis. Case Presentation: A 21-year-old Hispanic nulligravid woman presented with history of oligomenorrhea, weight gain and hirsutism. Her symptoms started after menarche at 15 years old with irregular periods, hair growth on her face and neck, and rapid weight gain. She was evaluated by an endocrinologist and was found to have an elevated total testosterone level by LC/MS on several different occasions: 309ng/dl, 259ng/dl and 229 ng/dl, as well as elevated androstenedione 346 ng/dl (41-262ng/dl). She was treated with metformin and oral contraceptive pill for two years and then referred for second opinion. On our physical exam, she had a BMI of 44.60 kg/ m2, a deep voice, Ferriman Gallwey score of 12 and acanthosis nigricans. OCPs were held for three months for accurate testing and work up revealed total testosterone 164.7 ng/dl (10.0-55.0 ng/dl), sex hormone binding globulin 25.4 nmol/L (24.6-112.0 nmol/L), bioavailable testosterone 84.3ng/dL (51.4%), DHEAs 375 µg/dl (110-431.7 µg/dl), and androstenedione 264 ng/dl (41-262 ng/dl). Other causes of hyperandrogenism such as hyperprolactinemia, hypothyroidism and congenital adrenal hyperplasia were ruled out. MRI pituitary from outside facility was reviewed and was normal. MRI abdomen and pelvis with/without contrast was performed, which demonstrated normal adrenal glands and an 8.1 cm midline pelvic cyst, containing a 0.7 cm enhancing solid nodule. She was referred for surgery for concern for possible virilizing tumor. The cyst was surgically removed and intra-operative ovarian exploration and cytopathology from pelvic washing were negative. She was referred for bariatric surgery and underwent a sleeve gastrectomy. After 6 weeks, she lost 30lbs, BMI improved to 37.1 kg/ m2 and her menses resumed. Repeat labs showed improvement in her androgens: total testosterone 64.8ng/dl, SHBG 104nmol/L, androstenedione 127ng/dl. After 8 months, she lost 110lbs and has dramatic improvement in her hirsutism and clearance of her acanthosis nigricans. Conclusion: Sustained lifestyle changes and weight loss are a mainstay in the treatment of patients with PCOS and obesity. Bariatric surgery results in durable weight loss and restores the normal physiological balance of sex hormones and improves signs and symptoms of hyperandrogenism. Presentation Date: Saturday, June 17, 2023