BACKGROUND: The number of reports of menstrual changes after COVID-19 vaccination in the Saudi population is still unknown. Therefore, this study aimed to assess the effect of the COVID-19 vaccine(Pfizer, AstraZeneca, and Moderna) on the menstrual cycle among females in Saudi Arabia.METHODS: This descriptive cross-sectional study was conducted in Saudi Arabia at Umm Al-Qura University (UQU) from August 2021 to February 2022. Data was collected through a previously validated online questionnaire.RESULTS: A total of 2338 participants who received the first dose of the COVID-19 vaccine participated in this study; 1606 (68.7%) of them received the second dose in addition to the first. The mean age of the study participants was 35.4±9.5 years. No significant associations were found between the type of COVID-19 vaccine and the impact on the menstrual cycle, either for the first or second dose (P-values > 0.05). A significant association was found only between the first dose vaccination day and the impact on the menstrual cycle in the second question of “After receiving the COVID-19 vaccine, your next period was” (P-value ≤ 0.05). Significant associations were found between the second dose vaccination day and the impact on the menstrual cycle in the first and second questions of “After receiving the COVID-19 vaccine, your next period was”, and “After receiving the first dose, your next period was," respectively (P-values ≤ 0.05).CONCLUSION: The study found a potential association between the COVID-19 vaccine and menstrual cycle irregularities, which could impact females' quality of life.KEYWORDS: COVID-19 Vaccine; Menstrual Cycle; Menstrual irregularities, Females; Women; Saudi Arabia