Introduction: Poor sleep quality is a critical occupational health problem for health care providers, particularly nurses especially during COVID-19 pandemic, that not only affects their physical and mental health, but also affects patient’s safety and job performance. Aim of Work: To measure the prevalence of poor sleep quality among Egyptian nurses during the pandemic of COVID 19 and to determine different factors affecting sleep quality. Materials and Methods: This web-based cross-sectional survey was conducted to assess sleep quality and its determinants among Egyptian nurses, during the period from September 2020 to February 2021 using self–administered validated Arabic version of Pittsburgh sleep quality index (PSQI). Results: The current study involved 351 Egyptian nurses, recruited from 15 Egyptian governorates. Most of them were less than 30 years old (73.2%); 75.5% were females and 56.1% were married. About 17% of nurses were working in isolation hospitals, 82.1% were night shifters, and (31.9%) had COVID-19 infection. Assessment of sleep quality, revealed that 83.5% had poor sleep quality (PSQI score>5), the most affected domain was sleep latency (1.72±0.86), whereas the least affected one was sleep medications use (0.35±0.79). Poor sleep quality was associated with young age, smokers, work experience less than 10 years, previous COVID-19 infection, working in isolation hospitals, night shifts, private work and long working hours. Conclusion and recommendations: The current study showed that there was high prevalence of poor sleep quality among the studied nurses during COVID-19 pandemic. Presence of chronic diseases, night shifts, private work and long working hours / week were significant predictors of poor sleep quality among participants which indicated the need for well-organized work schedules for nurses. Work place periodic health assessments and management of sleep disorders are essential, with more attention to wellness and coping programs at all health facilities, especially those involved in fighting COVID-19.