Purpose: This study was conducted to develop a mother-fetus interaction promotion program aimed at enhancing the sensitivity of primiparas, and to evaluate the effects of a mother-infant play interaction. Method: Participants were recruited from OB-GY clinic with postpartum take-care center (17 mother-infant dyads for intervention group and 17 dyads for control group). Data were collected from January 18 to August 5, 2005. For the intervention group, programmed education which focused on mother-fetus interaction in the 3rd trimester was given. For the two groups, home visiting or a postpartum care center was used for data collection of the mother-infant interaction which was conducted at postpartum 1 week and 1 month. Also mother-infant interactions during feeding were videotaped and two trained observers analyzed the tapes. Results: A significant difference was found in mother-infant interaction between the two groups (postpartum 1 week, t=6.10, P=0.000, 1 month t=6.69, p=.000). For variations in mother-infant interaction in the control group, a significant difference was found in between postpartum 1 week and 1 month (t=-2.564, p=.021). In subscale analysis, interactional behavior of the infant significantly increased in both groups. Conclusion: This study showed that the mother-fetus interaction promotion program aimed at promoting mother-infant interaction increase maternal sensitivity. Therefore, this study suggests that this nursing intervention to increase maternal sensitivity to the fetus should be broadly applied with primiparas, as it can be beneficial for formation of the mother-infant relationship, and for promotion of the social, emotional, and cognitive developments of the children.