BACKGROUND: Sleep disturbance is particularly common among medical students worldwide and affects their wellbeing and academic performance. However, little is known about this issue in Yemen. This study looks at sleep quality and its association with personal and life-style factors and self-reported academic performance among medical students at the largest Yemeni university. METHODS: A cross-sectional survey was conducted at Sana'a University, Yemen, in 2017. The Pittsburgh Sleep Quality Index (PSQI), consisting of 19 items and 7 components (score range = 0-3), was used to assess sleep quality. The summation of the components' scores yields the global PSQI score (range = 0-21). A global PSQI value higher than 5 indicates poor quality of sleep. Logistic regression was applied to look at relationships. RESULTS: 240 male (41%) and female (59%) medical students took part in the study with 54% being preclinical and 46% clinical with an average age of 23.3 years (SD = 1.7). The mean global score (SD) was 6.85 (2.8), and 68% of the students (N = 163) were identified as poor sleepers. The mean global PSQI score (SD) and proportion of poor sleepers were higher among males (7.7 (2.8) and 81%, respectively) than females (6.27 (2.42) and 59.2%, respectively), p ≤ 0.001. Good sleep quality was more likely (OR (95% CI)) among females (3.4 (1.3-8.8)), the unmarried (2.8 (1-7.8)), those in good health (2.3 (1.1-4.5)), and nonkhat chewers (4.9 (1.4-17.1)). Nonsmokers were less likely to have good quality sleep compared to occasional smokers (0.185 (0.071-.485)). Stress (30%) and academic workload (21%) were the most commonly reported causes of poor sleep quality. Almost two-thirds of the students (65%) mentioned that disturbed sleep undermined their academic performance. CONCLUSIONS: Poor sleep quality is common among Sana'a medical students and impacts their academic performance. Specific stress management and sleep hygiene promoting programs should be incorporated early on in medical education.