Background: Vitamin D plays a very important role in the human body. In Saudi Arabia, the sun exposure is limited for many reasons. The use of vitamin D-fortified food or supplements may complement the daily body requirements. The knowledge and perception of the general population towards vitamin D-fortified intake in Makkah, Saudi Arabia, are not known. Saudi Arabia has one of the highest reported incidences of vitamin D deficiency in studies conducted worldwide. However, there has been very limited exploration of vitamin D related knowledge, attitudes and practices among female adult in Saudi Arabia. However, the case of vitamin deficiency is reported to increase in many female Saudi Arabia worldwide, especially in Saudi Arabia. Mothers, having adequate knowledge about vitamin D and its supplementation, may lead to possible lowering of the cases of vitamin D deficiency and its complications. Ami of the study: To assessment the impact of Knowledge regarding Vitamin D deficiency among female adult attending the Primary Health clinic at Makkah, Saudi Arabia, 2022. Methods: This was an analytical cross-sectional study conducted during 2022, among female adult attending the Primary Health clinic at Makkah AL-Mokarramah random sampling technique was applied and an Arabic self-administered questionnaire used for data collection. Result: shows that most of the participants (37.0%) were in the age 25-30 years also regarding level of education the majority of participant are Secondary education were(34.0%). Regarding Marital status the majority of participant are married were (58.0%). Regarding the Economic level the majority of participant Average were (45.0%). Regarding the Chronic disease the majority of participant No were (72.0%). Conclusion: The low levels of knowledge about vitamin D and low consumption of vitamin despite the population in the current study having a moderate level of knowledge about vitamin D-fortified food, the practices towards intake of vitamin D-fortified food or supplements are still underused. Supplementation, including vitamin D, calcium, multivitamin, and calcium supplements with vitamin D, may have contributed to the higher prevalence of vitamin D deficiency among the female adult.