The purpose of this study was to investigate. the effects of the lactation of human or bovine milk and the method of using nursing bottles on the salivary invertase test scores and deciduous caries experience of children. 328 preschool children (boys 178, girls 150) in Iksan city were selected for this study. The parents of the children were asked to answer the questionnaire about the lactation of human or bovine milk and the time of using nursing bottles. The data were obtained from the salvary invertase activity score,(Resazurin Disc Test) deciduous caries experience and the questionnaire. The result were as follows. The invertase activity and caries experience of the human milk higher than that of the bovine milk group(P<0.05). There were significant positive relationships between the lactation period and the invertase activity and between the lactation period and the caries experience(P<0.05). Caries experience had a tendency to increase as the time of using nursing bottles increase (P>0.05).