Background: Menopause simply means the stoppage of menstruation. It also refers to the changes women go through around this period. Vitamin D deficiency is more common in premenopausal women than previously thought and it may impair quality of life mainly due to lack of awareness about the importance of vitamin D and prevention of its deficiency. Aim: This study aimed to investigate the impact of educational guidelines on premenopausal women's knowledge, attitude, and practices regarding vitamin D deficiency. Research design: A quasi-experimental (Pre-post-test) research design was used to achieve the aim of this study. Sample: A Purposive sample included 300 premenopausal women. Setting: The study was conducted in a gynecology outpatient clinic at Sohag University Hospital. Tools: four tools were used to collect the data as follows: Tool (I): Structured interviewing questionnaire to assess premenopausal women's personal characteristics and their knowledge regarding vitamin D deficiency, Tool (II):  Lirket scale to assess premenopausal women's attitude regarding vitamin D deficiency, and Tool (III):  Premenopausal women's practice regarding vitamin D deficiency. Result: The study revealed that there were statistically significant improvements in knowledge, attitudes, and practice among premenopausal women pre & post-training educational guidelines (P<0.001). The total knowledge score, total attitude, and total practice of the studied sample showed a positive correlation regarding vitamin D deficiency p<0.001. Conclusion: The study concluded that educational guidelines had a positive effect on improving premenopausal women's knowledge, attitudes, and practice regarding vitamin D deficiency. Recommendations: There is a need for creating simple Arabic printed educational materials such as (booklets, pamphlets, and posters) regarding vitamin D deficiency can improve Knowledge, attitudes, and practice among premenopausal women. Replication of the current study with a larger sample in different settings is required to generalize the results.