Background: Many rumors and misinformation disseminated among people due to fear associated with an explosion of COVID-19 cases. Objectives: To assess the level of knowledge, identify common misconceptions about COVID-19 and their demographic determinants among health staff. Subjects and methods: A cross-sectional study was done among a sample of healthcare workers who work in primary healthcare centers or outpatient units of general hospitals located in Makkah city, Saudi Arabia during period from February to April–2021. A structured online questionnaire was used for data collection, including sociodemographic factors and 19 questions to assess healthcare workers knowledge about COVID-19. Results: The study included 434 healthcare workers. Their age ranged between 23 and 60 years with an arithmetic mean (±) standard deviation of 30.4±6.4 years. History of having any previous training to deal with situations related to COVID-19 pandemic was observed among 54.6%. The main sources of information about COVID-19 were medical literature (36.9%) and government statement (29.5%). Overall, majority of healthcare workers (82.5%) expressed adequate knowledge. Widowed healthcare workers (mean rank=363), those experienced between 5 and 10 years (mean rank=227.70), those who experienced any previous training to deal with situations related to COVID-19 pandemic (mean rank was 233.18) and those who reported medical literature as the main source of information (mean rank=256.90) were more knowledgeable compared to their peers. Conclusion: Majority of healthcare workers expressed adequate knowledge regarding COVID-19 pandemic. However, some misconceptions were identified. Therefore, well-organized continuous educational sessions are needed to improve the knowledge and clarify some misconceptions.