Background: Hypothermia is a major factor in infant`s morbidity and mortality in developing countries. So, maintaining normal body temperature in preterm infants is crucial. Aim of study: The aim of this study was to assess nurses' knowledge and practices regarding hypothermia for preterm infants. Design: A descriptive design was utilized to conduct this study. Settings: This study was carried out in neonatal intensive care units of Benha University hospital, and Benha Specialized Pediatric Hospital at Benha city. Sample: A convenient sample of 150 nurses and 200 preterm infants were taken from the previous mentioned hospitals. Tools of data collection: Two tools were used: tool (1): Arabic structured interviewing questionnaire and tool (2): An observational check list. Results: Slightly more than one third of the studied nurses were in age groups less than 30 years with mean ± SD (33.16±8.04) years old, two fifth of the studied nurses have diploma of technical institute of nursing and have experience equal 15 years or more. More than half of the studied nurses had average knowledge level regarding hypothermia and more than two thirds of them had poor practices. Conclusion: There was a highly statistically significant relation between total nurses` knowledge and practices regarding prevention of hypothermia with their characteristics. Again, there was a highly statistically significant positive correlation between the studied nurses` total knowledge scores and their total practices scores. Recommendations: The importance of developing periodical training programs for all nurses working at Neonatal Intensive Care Units regarding care of preterm infants with hypothermia to update their performance.