Background and Aims: Anxiety is one of the symptoms of menopause, which is due to stopping of ovarian activity. The aim of this study was to investigate the effect of Foeniculum vulgare L. extract on anxiety-like behaviors in ovariectomized mice.Methods: Eighty female mice weighing 25-30 g and aged 6-8 weeks were divided into 10 groups of eight each, controls: the group without ovariectomy given distilled water, positive controls: the ovariectomized group receiving 40 µg/kg of estradiol valerate, the groups without ovariectomy given F. vulgare extract by gavage at 200, 500, and 750 mg/kg, the ovariectomized group given distilled water, the ovariectomized groups given F. vulgare extract at 200, 500, and 750 mg/kg, and the ovariectomized group given diazepam at 1 mg/kg. Elevated plus maze (EPM) and open field were used to investigate anxiety in mice. The level of malondialdehyde (MDA) and total antioxidant capacity (TAC) of the brain and serum were also measured. Results: In ovariectomized mice, the number of entries to the closed arms of EPM was significantly increased compared with control group (P<0.05). Treatment of ovariectomized mice with 500 and 750 mg/kg of the extract significantly increased the number of entries to the open arms and significantly decreased the number of entries to the closed arms of EPM (P<0.05). The time spent in the center and the crossing squares in the open field significantly decreased in ovariectomized mice compared with control group and treatment with estradiol significantly increased them (P<0.05). In ovariectomized mice, serum and brain MDA levels significantly increased and their TAC significantly decreased compared with control group. Different doses of extract, estradiol and diazepam significantly reduced MDA levels and increased TAC in both brain and serum (P<0.05).Conclusion: vulgare extract may ameliorate the symptoms of anxiety in ovariectomized mice by reducing oxidative stress
