Pregnancy is unique and critical time in the life course of a woman. There occurs a lot of changes in mothers body and mind during pregnancy. Her body will change physiologically in order to accommodate the growing fetus. For the optimum development of the fetus, like all other factors maternal nutrition is one of the important factors. Optimum nutrition help in optimum weight gain, which has got relation with both maternal and fetal outcome. The objectives of the present study were to assess the relationship between gestational weight gain and perinatal outcome, to find out the association between gestational weight gain with selected maternal demographic variables. The study was non experimental descriptive in nature, which included 100 postnatal mothers. Demographic data and obstetrical history were collected by interviewing, self-reported pregravid weight were recorded and gestational weight gain was calculated by subtracting the pregravid weight from the weight which was recorded at the time of admission for delivery. Data regarding perinatal outcome (includes maternal outcome and neonatal outcome) was collected from the medical records of both mother and baby. Maternal socio demographic data and obstetrical history were analysed in terms of frequency and percentage. Gestational weight gain was categorized as normal, less than normal, excess on the basis of IOM guidelines. Association between gestational weight gain and perinatal outcome was analyzed by chi square test. The result of the study shown that there is significant association between gestational weight gain and mode of delivery, gestational age at birth, birth weight of the baby, size of the baby, APGAR score at 5minute<7, and development of neonatal jaundice and maternal age, monthly income of the family and type of residence(urban/rural).