Depression is one of the most common psychiatric disorders with a prevalence of 15%-25%. Monoamine aminotransferases, in particular, norepinephrine, serotonin, and dopamine, change in the brain of depressed people. Adiantum capillus-veneris is one of the species of the maidenhair fern genus that have traditionally been used to treat cough, cold symptoms, and local hair loss.In this experimental study, white male rats weighing 250-300 g were assigned to 5 groups of 10 each; group 1: Receiving normal saline; groups 2-4: Receiving A.capillus-veneris extract at 50, 100, and 200 mg/kg, respectively; and group 5: Receiving fluoxetine at 10 mg/kg. Chronic unpredictable stress (CUS) was induced by 3-week exposure to chronic stress. The forced swim test and plus maze were used to assess depression and anxiety, respectively. Malondialdehyde (MDA) levels and antioxidant capacity in the serum and brain were measured. Treatment with A.capillus-veneris extract at 200 mg/kg significantly reduced the duration of immobility. In the group given extract at 200 mg/kg, a significant increase in the number of open arm entries was observed when compared to the control group. A.capillus-veneris extract at 50, 100, and 200 mg/kg resulted in a significant increase in the time spent in the open arm. A.capillus-veneris extract reduced MDA levels and increased antioxidant levels of serum and brain in rat. A.capillus-veneris has significant antidepressant and anti-anxiety effects in rat, probably due to its antioxidant and anti-inflammatory activities.