Purpose <p>Oral contraceptives (OCs) are commonly used for the treatment of polycystic ovarian syndrome (PCOS). However, the therapeutic effects of OCs on cognitive function have not been explored extensively. This study aimed to determine the changes in cognitive function in PCOS patients treated with three cycles of combined oral contraceptives (COCs) containing estrogen and progesterone.</p> Methods <p>Drug-naive PCOS patients (<i>N</i> = 35), aged 18–35 years, were evaluated at baseline and three months after treatment with COC containing levonorgestrel (0.15&#xa0;mg) plus ethinyl estradiol (30&#xa0;µg). Working memory (WM), attention, and executive function domains of cognition were assessed using the auditory and visual digit span test (DST), continuous performance test-identical pair (CPT-IP), and trail-making test (TMT), respectively.</p> Results <p>The DST results showed improvements in the maximal digit span (ML) of the auditory (<i>p</i> = 0.0039) and visual (<i>p</i> = 0.0005) WM tasks after treatment. Improvements were also observed in the mean span (MS) of the auditory (Cohen’s d = 0.94, <i>p</i> = 0.0009) and visual (Cohen’s d = 0.90, <i>p</i> &lt; 0.0001) DST after treatment. In CPT-IP test, the mean reaction time (RT) of hit rate (Cohen’s d = 0.64, <i>p</i> = 0.01) and random errors (Cohen’s d = 0.64, <i>p</i> = 0.01) showed a significant decrease after treatment. After treatment, TMT showed a significant decrease in all parameters, except trail 1 errors (<i>p</i> = 0.1079).</p> Conclusions <p>This preliminary study suggests that three months of COCs treatment in PCOS patients improves cognitive performance in the domains of WM, attention, and executive function. However, the lack of a control group and short follow-up period limits the strength of our findings.</p>