The effects of maternal antenatal and postnatal anxiety and depression on infant negative behavioral reactivity were examined in a sample of 22 mother-infant pairs. Maternal anxiety and depression were assessed by standardized measures during the third trimester of pregnancy and postpartum. Infant negative behavioral responses to novelty were assessed using a previously validated measure at 4 months of age. Maternal anxiety and depression during the prenatal, but not the postnatal period, were related to infant negative behavioral reactivity to novelty. These data illustrate that prenatal maternal psychological state can exert persisting influences on human infant behavior. (Contains 4 tables and 2 figures.)