Objective: To compare the effects of metformin and chromium pico- linate on females with polycystic ovarian syndrome. Background: Polycystic ovarian syndrome is the most common en- docrinopathy of reproductive-aged women. It presented with exces- sive hair growth(hyperandrogenism), menstrual irregularities (an- ovulation), and polycystic ovaries.They are commonly accompanied by obesity, insulin resistance, and infertility. Methods: Sixty female patients with polycystic ovarian syndrome were enrolled for our study at Suez Canal University Hospitals, from January 2016 to December 2016. They were randomly assigned into 2 groups. FSH, LH, testosterone, TSH, prolactin, fasting blood sug- ar, fasting insulin, QUICKI, HOMA-IR were measured for all pa- tients. The first group received metformin 500 mg twice daily while the other group received chromium picolinate 200 μg once daily for 3 months. Results: Fifty-four patients completed the study, we compared the effect of metformin and chromium in patients with PCOs, it showed significant difference regarding free testosterone, serum prolactin (p=0.01), FSH level, FBS, Fasting insulin and QUIKI between the two groups (p=0.001). In Group I, there was significant difference regarding the values of BMI, free testosterone, TSH, fasting blood sugar, fasting insulin, HOMA-IR, QUICKI, ovarian volume(p <0.001)prolactin (p=0.01), and hirsutism score (0.02) before and after treatment with metformin. In Group II, there were significant differences regarding the values of testosterone (p=0.01), BMI LH, FSH, TSH, fasting blood sugar, fasting insulin, HOMA-IR, QUICKI, ovarian volume and hirsutism score before and after treatment with chromium picolinate(p =0.001). After treatment, twenty-two (81.48%) patients had normal men- struation in Group I compared to 24 (88.89%) patients in Group     II (p=0.35) meanwhile, 11(40.7%) patients had normal ovulation   in Group I compared to 12 (44.4%) patients in Group II (p=0.78). Pregnancy occurred in 6 (22.2%) patients in group I and 5 (18.5%) patients in Group II with no significant difference (p=0.73). After 3 months of treatment, there were no significant differences between the groups regarding the side effects except abdominal discomfort which was more significant with metformin (p= 0.018). Conclusion: Chromium picolinate was better tol- erated than metformin due to lower side effects; nevertheless, no significant differences were ob- served between the two groups regarding ovula- tion and pregnancy rates. Therefore, metformin could be replaced by chromium in some PCOS patients.