Background and purpose: Maintaining a normothermic state is an essential newborn care during the first few weeks of life. The most cost effective management strategy for hypothermia is its prevention and it can be done by the mothers of a neonate. So, the mother has to be educated regarding the various measures of thermoregulation .The purpose of the present study is to assess the effect of video assisted structured teaching programme on knowledge regarding prevention of hypothermia among mothers of preterm babies. Materials and methods: A pre-experimental study with simple random sampling (lottery) technique was used to select the 55 postnatal mothers who fulfilled the inclusion criteria. After obtaining formal permission from the institution and written informed consent from the mother of preterm babies, pre-test was conducted by interview method using the structured questionnaire. On the same day 20 minutes video assisted structured teaching programme was given through lecture-cum-discussion to the mother. The video had information regarding importance of temperature control in preterm neonates, management of hypothermia, importance of breastfeeding, kangaroo mother care in prevention of hypothermia and complication of hypothermia. On third day post-test was conducted using the same questionnaire. For analyzing the data, descriptive statistics (frequency, percentage, mean and standard deviation) and inferential statistics (paired t-test, chi-square) were used. All the statistical analysis had done with 5% level of significance. Results: The results showed that the mean score was increased from the pre-test score of 10.91± 3.576 to post-test score of 20.36 ± 2.908 and it was found to be statistically significant at 0.001 level. There is also significant association of pretest knowledge categories with some of the socio-demographic variables of the mother like education, place of residence, previous knowledge and sources of information regarding prevention of hypothermia among mothers of preterm babies. Conclusions: The present study revealed that video assisted structured teaching programme on knowledge regarding prevention of hypothermia improved the knowledge of mothers of preterm babies.