Background: Vitamin D insufficiency is a common health issue widespread throughout the world; however, there are numerous groups that are on the highest risk of insufficiency. The insufficiency of vitamin D is the grand restrainable and preventable challenge throughout the world. COVID-19 outbreak is a significant health issue and has a universal attention with extant the pandemic of COVID-19 and the growing cases infected by it. Health care workers' women have the superior risk of exposure for COVID-19 among the population cannot be overlooked. Aim: Assessing knowledge practices, and attitudes, regarding vitamin D insufficiency amongst health care workers' women with COVID-19, in obstetrics and gynecological hospital Ain shams university. Explore the relation between serum vitamin D level of health care workers' women and severity of COVID-19 symptoms. Methods: A Descriptive-analysis study was proceeded at COVID -19 outpatient clinic at maternity and gynecological hospital, Ain Shams University, from onset of February to the ending of April 2021. A purposive sample of 68 health care workers' women with confirmed COVID-19. Data were gathered through four main tools. The first, structured interviews questionnaire which consisted of two parts, the first was to assessing demographic and clinical features of the studied health care workers' women with COVID-19. The second part was the laboratory analysis of serum levels of 25-hydroxy vitamin D using the electrochemiluminesence immunoassay technique on Cobas e411 immunoassay analyzer-Hitachi Ltd-Japan. The second, a self-administered google form online questionnaire was utilized to evaluate confirmed COVID-19 health care workers' women knowledge, regarding vitamin D. The third: A self-reported practices google form online questionnaire was utilized to evaluate confirmed COVID-19 health care workers' women practices for vitamin D ingestion and habitual sun exposure, The fourth: A selfadministered google form online questionnaire was utilized to assessing confirmed COVID-19 health care workers' women attitude on behalf of vitamin D insufficiency. Results: Demonstrated that the confirmed COVID-19 health care workers women' mean age' was 40.9± 8.7years. Whereas (7%) of studied participants were had vitamin D sufficiency, (78%) had vitamin D insufficiency and (15%) had vitamin D deficiency with total mean ± SD (16.8 ± 8.9). Whilst mean ± SD of the total vitamin D knowledge scores was (49.8 ± 16.1) and (23.5%) of studied participants had sufficient knowledge and (76.5%) had insufficient knowledge. While (25%) of studied participants had adequate practice, (75%) had inadequate practice. Moreover (51.5%) of studied participants had positive attitude, and (48.5%) had negative attitude. A statistically significant relationship between majority COVID-19 symptoms in confirmed COVID-19 health care workers' women and their vitamin D level. Conclusion: The study displayed that mostly of health care workers' women with COVID-19, had insufficient knowledge regarding to vitamin D, had ...