Background: Maternal nutritional status is important for health and quality of life in women and growing fetus. Maternal weight gain in pregnancy can offer a good means of assessing the wellbeing of the pregnant mother and her baby. Inadequate prenatal weight gain is a significant risk factor for intrauterine growth restriction, preterm delivery and low birth weight in infants. Obesity and excessive weight gain on the other hand can lead to adverse maternal and fetal outcomes. Interestingly, to get a good fetomaternal perinatal outcome mode of delivery decision is also changed with BMI. Objective: The aim of the study was to evaluate the effect of maternal BMI on the mode of delivery. Methods: This cross-sectional study was carried out department of obstetrics and gynaecology at Bangabandhu Sheikh Mujib Medical University. A total 100 population of purposive sampling was the methods of choice to select the sample from the hospital admitted patients during the period from August 2016 to December 2017. Results: The mean age of 100 mothers were 28.4 (± 6.2) years. The maximum mothers attended from 3rd trimester were overweight (55.36%) whereas 44.64% from the same trimester were normal BMI mothers. Maximum mothers (27%) were from 25-29 years age group and the minimum mothers (4%) were from >= 40 years. Forty Seven Percent mothers came as primigravida. Primigravid women and multigravida with LSCS and without LSCS showed different mode of deliveries. The more the gravida with history of caesarean section the more frequency of present occasion of CS (p=0.006). The higher BMI showed more frequency of caesarean section than NVD or assisted delivery (p=<0.00001) Multiparous women showed more BMI than the p nulliparous. (p=0.005). Multiparity, maternal age and pre-existing medical conditions revealed more complicated labor. Conclusion: The more BMI of mother showed more frequency of caesarean section, assisted delivery than the normal vaginal delivery.