Background: There is growing concerns that COVID-19 vaccination causes disruption to menstrual cycle. The study has showed that several women required gynecological visits claiming menstrual irregularities or abnormal uterine bleeding after the first and second doses of vaccination (regardless of the type of vaccine used). Objective: This study was conducted in the eastern province of Saudi Arabia to assess the effect of Covid-19 vaccination on the menstrual cycle of the women. Material and methods: It was a cross-sectional prospective study that was conducted by survey the post Covid-19 vaccinated women in the eastern province of Saudi Arabia. The sample size was calculated using a Fisher's formula which was 344 women who have been vaccinated by Covid-19 vaccination. Results: A total of 343 women participated in this study. The mean age of the participants was 30.16 ± 18.20 years. More than forty two percent of the participants had one time Covid-19 infection while 5% was twice infected with Covid-19 virus. The vast majority of the participants (91.3%) were immuned by 2 vaccines. More than sixty percent (60.3%) of the participants were suffering from one and other menstruation irregularities after Covid-19 vaccination. 14% of them were suffering from the menstruation frequency longer than 35 days while 10.2% of them were suffering from the menstruation frequency shorter than 25 days. Conclusion: Coronavirus disease 2019 (COVID-19) vaccination is associated with change in menstrual cycle length, heavy menstruation and painful menstruation. Female with the age group of 15-24 years were 2 times more likely to develop menstruation cycle change.