BACKGROUND: Cowden syndrome is an autosomal-dominant condition associated with mutations in the tumor suppressor gene PTEN. Gynecologic malignancies are common with a 5-10% risk of endometrial cancer and 25-50% risk of breast cancer. CASE: A 37-year-old woman with a history of breast cancer, other neoplasms, and multiple skin lesions was diagnosed with Cowden syndrome after a germline PTEN mutation was identified. The endometrium had high glucose uptake on positron emission tomography scan and was irregularly thickened on ultrasonography; biopsy revealed endometrial polyps and simple hyperplasia. Fifteen months later, hysteroscopy again confirmed numerous benign endometrial polyps. CONCLUSION: Recurrent, multiple endometrial polyps portend a high risk of endometrial cancer in women with Cowden syndrome. Monitoring for malignancy and consideration of hysterectomy after childbearing is completed is warranted.