Purpose: The purpose of this study was the influencing variables of maternal weight gain and neonatal birth weight in full term pregnancies. Method: The subjects were 136 mothers in full term pregnancies(38-42 weeks) and her babies who were selected from 2 general hospital in Pusan. The data were collected from June 14th to October 14th in 2004. Data were obtained by questionnaires. Results: The maternal weight gains was lesser that the pregravid weights was the lower (F=3.410, p=.011). The volumes of weight gains of mothers that had alcohol drinking(t=6.259, p=.014), caffeine consumption (t=4.137, p=.044) were lesser than not. And the birth weight were influenced by passive smoking(t=4.017, p=.047), caffeine consumption (t=5.954, p=.016). Conclusion: The results of this research confirm that the maternal weight gains were influenced by pregravid weight, alcohol drink, caffeine consumption. And the birth weight were influenced by passive smoking, caffeine consumption.