Administration of thymoquinone in both dosages (5 and 10 mg/kg) significantly decreased the level of LH (p < 0.05 and p < 0.05), LH/FSH ratio (p < 0.05 and p < 0.05) and testosterone (p < 0.01 and p < 0.05) in PCOS groups and caused them to reach to the level of the control group. The gene discussed is PLOD1; the disease is polycystic ovary syndrome.