Background: Autoimmunity has been proposed in the pathogenesis of polycystic ovary syndrome (PCOS) since early 1990s. Studies of anti-ovarian antibodies (AOA) that were performed so far yielded conflicting results. Objective: This study aimed at evaluating the association between PCOS and AOA. Patients and method: The study was conducted on 80 Egyptian women who were divided into two groups: cases group of 40 women with PCOS, and a control group of 40 healthy age-matched normally cycling fertile women. For both cases and control groups, serum level of AOA was measured using ELISA. Results: Serum AOA level was significantly higher among cases than controls (p value < 0.05). No significant difference was found between cases and controls regarding their hormonal profile (estrogen, FSH, LH, and testosterone) except for the level of mid luteal progesterone which was significantly lower among cases (p value <0.05). No significant correlation was found between AOA and age, body mass index (BMI), FSH, LH, E2, mid luteal progesterone and testosterone in control group. However, a significant negative correlation between AOA and serum testosterone level was found in PCOS group. Conclusion: Our results suggest that autoimmune ovaritis may be frequently associated with PCOS. Circulating AOA may represent a practical and suitable marker for diagnosis of PCOS.