Background: Prenatal exposure to infectious and/or inflammatory insults can increase the risk of developing neuropsychiatric disorder such as bipolar disorder, autism, and schizophrenia later in life. We investigated whether Valeriana fauriei (VF) treatment alleviates prepulse inhibition (PPI) deficits and social interaction impairment induced by maternal immune activation (MIA).Methods and Results: Pregnant mice were exposed to polyriboinosinic-polyribocytidilic acid (5㎎/㎏, viral infection mimic) on gestational day 9. The adolescent offspring received daily oral treatment with VF (100㎎/㎏) and injections of clozapine (5㎎/㎏) for 30 days starting on the postnatal day 35. The effects of VF extract treatment on behavioral activity impairment and protein expression were investigated using the PPI analysis, forced swim test (FST), open field test (OFT), social interaction test (SIT), and immunohistochemistry. The MIA-induced offspring showed deficits in the PPI, FST, OFT, and SIT compared to their non MIAinduced counterparts. Treatment with the VF extract significantly recovered the sensorimotor gating deficits and partially recovered the aggressive behavior observed in the SIT. The VF extract also reversed the downregulation of protein expression induced by MIA in the medial prefrontal cortex.Conclusions: Our results provide initial evidence of the fact that the VF extract could reverse MIA-induced behavioral impairment and prevent neurodevelopmental disorders such as schizophrenia.