The purpose of this study is to identify the major sources generating big data in health sector in the Sultanate of Oman, to find out how significant is this data and in what fields it can be invested, as well as its role in managing Covid-19 crises. Moreover, the study points out the legalizations and laws followed in using big data in health sector and identifying the major challenges facing users in getting real values out of this data. The study relies on the qualitative descriptive approach. Semi-structured personal interview is used in collecting data,(18) interviews were conducted. The study community includes both government and private health institutions in Oman. The study sample consists of (3) government hospitals, one private hospital in addition to the Ministry of health. The specialties of the sample members varied, as the focus is on those dealing directly with data, such as: IT specialists, statisticians, and medical records personnel. A number of medical specialties have been added, such as: a doctor, a nurse, and a pharmacist. The most important results of the study includes: the electronic health systems are considered as one of the most important sources of big date in the health sector in Oman. The results reveals that big data is very important in health sector for medical diagnosis, prescribe appropriate medication to the patient and taking the right decisions based on data. Furthermore, big data is used in Artificial intelligence technology, making surveys, studies and researches, reducing costs for health institutions, predicting diseases, and directing the use of medical resources. During Covid-19 crisis, big data plays a prominent role in managing this crisis through the electronic medical records for Covid-19 patients, which contributes in providing accurate data on patients at the time of the pandemic through quick access to demographic data and addresses of patients which helps a lot in the epidemiological investigations, and determine the areas where the epidemic is spreading. The results of this study shows that there is no comprehensive law on health data, weather about personal information or data related to patient's medical history. Regarding these regulations, it is based on a number of existing laws such as: Information Security Act issued by Information Technology Authority, Infectious Diseases Act which is updated during Covid-19 pandemic, Information and Statistics law and the Law Governing the Practice of the Medical Profession and Allied Health Professions. In some health institutions, internal laws are set up as a kind of workflow organizing. The study concluded in some recommendations. The most important of them include: cooperation between the government and private health sectors in order to find out a national data system includes all health fields which facilitates access to patients health information if necessary, the importance of establishing clear policies and legislations for big data use in the health sector.