Background: Many scientists believe that elevated insulin levels are the primary cause of polycystic ovarian syndrome (PCOS). The hyperinsulinemia of obese women can be lowered by taking thioctic acid (Thioctacid-HR). Objective: The aim of the current work was to evaluate the effect of thioctic acid (Thioctacid-HR) on hyperinsulinemia, insulin resistance, menstrual function, and the volume of the ovaries in patients with PCOS. Patients and methods: This comparative, interventional, prospective randomized clinical study included a total of 38 women with PCOS, attending at Gynecologic Oncology Unit, Department of Obstetrics and Gynecology, Faculty of Medicine, Zagazig University Hospitals. Patients were randomly assigned into two equal sized groups of 19 subjects each by closed envelop technique as follow: group I (Case group) received Thioctic acid for 3 months and group II (Control Group) with no interventional treatment. Results: Regarding fasting and post prandial insulin, there were no significant differences between 2 groups. Taking of thioctic acid (Thioctacid-HR) for 6 months resulted in a significant decrease in the fasting and post prandial insulin after treatment. Also, there was a significant decrease in HOMA-IR after treatment. Conclusion: It could be concluded that thioctic acid has significant effect on PCOs clinically but no effect on ultrasound findings. Also, it decreases insulin level after 6 months. Therefore, Thioctic acid could help in treatment of PCOS.