The purpose of this study is to explore the effects of paternal deprivation ( PD) on offspring social interaction of the same sex and neuronal activation of relative nucleus in Mandarin Voles ( Microtus mandarinus). The results of social interaction tests showed that male mandarin voles whose fathers were deprived had significantly less investigating behavior and body contact(P < 0. 01),while female mandarin voles whose fathers were deprived showed less staring and self-grooming behaviors( P < 0. 05); however,both male and female mandarin voles whose fathers were deprived displayed longer duration of inaction( P < 0. 05) than their controls. The number of Fos immunoreactivity ( Fos-IR) neurons in male mandarin voles whose fathers were deprived was significantly higher in the bed nucleus of the stria terminalis ( BST) ( P < 0. 01 ),the paraventricular nucleus of the hypothalamus (PVN) (P < 0. 05)and the central nucleus of the amygdale (Ce)(P < 0. 05); the number of Fos-IR neurons in female mandarin voles whose fathers were deprived were also significantly higher in the BST and PVN ( P < 0. 01 ) compared to the control. The results reveal that social interactions and spontaneous activities of the offspring of mandarin voles may be reduced due to paternal deprivation,and that neural activation of brain regions associated with response to social stress might be significantly enhanced.