Background: COVID-19, defined as coronavirus disease 2019, is a widespread illness that happened due to the emergent infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), that induced a severe health concern with its outbreak. Aim: To measure the serum Vitamin D level in North Sinai Governorate cases infected by coronavirus-19 and correlate its level with clinical, laboratory biomarkers, severity and prognosis of the disease. Patients and methods: This prospective research has been performed on fifty Egyptian cases who were selected from cases attending the inpatient of North Sinai Hospitals (North Sinai Governorate), Egypt. All cases were found to be infected with coronavirus -19. Results: Mean serum vitamin D (Vit. D) was 24.53 ±8.93. According to prognosis, thirty-one (sixty-two percent) cases were discharged and nineteen (thirty eight percent) died. There was significant positive correlation between Vitamin. D and severity of coronavirus-19. Mean O₂ saturation on admission was 85±7.  According to clinical symptoms, fifty (hundred percent) cases had fever, sore throat, cough, arthralgia, myalgia, eight (sixteen percent) cases had diarrhea, twenty-one (forty-two percent) cases had abdominal pain, three (six percent) cases had vomiting and forty-five (ninety percent) cases had shortness of breath. Conclusion: This study demonstrated that there was a correlation between severity of coronavirus-19 and Vit. D. Further prospective studies with larger scales are necessary for confirming our results.