Background: Poor sleep quality is an important public health problem with multiple unfavourable consequences. Sleep disorders are widespread among university students and have a significant impact on their general health and academic performance. Aim: To investigate the relationship between sleep quality and academic performance among medical students in Menoufia University. Participants and methods: This cross-sectional study was carried out from 1 st November 2021 to the end of March 2022 on 1033 undergraduate medical students from Menoufia University in Egypt. The data were collected using self-administered questionnaire to obtain information regarding sociodemographic variables, academic achievement in the previous year, sleep habits and environmental sleep factors like smoking, exercise and media use. The Pittsburgh Sleep Quality Index (PSQI) was used to assess sleep quality. Results:The mean overall score of the PSQI was 18.03 (SD ± 7.59); the majority of students (96.5%) had bad sleep quality with PSQI score greater than 5. There was a highly significant difference between good and bad academic performance regarding Pittsburgh sleep quality score. Mean sleep duration was 6.67 (SD ± 2.05) hours. Most of participants were non-smokers (91.9%), physically not active (50.6%), and use the internet for more than two hours daily (55.8%). Conclusion:Poor sleep is a major problem for Egyptian medical students, and there was also a significant relationship between sleep quality and academic performance.