CCOVID‐19 Vaccines are currently the leading approach for combating the pandemic's advance. Despite, their protective effect has been frequently addressed but little knowledge is available regarding menstrual changes after the covid-19 vaccine. Aim: The study aimed to assess menstrual changes associated with COVID-19 vaccine among adolescent females. Design: A descriptive comparative cross-sectional study. Sample: A convenient sample of 412 adolescent females applied in Beni-Suef City through social media such as Facebook and WhatsApp groups. Tools: Data were collected using three online questionnaires including 1) Socio-demographic characteristics 2) Assessment of menstrual characteristics 3) Beck Anxiety Inventory (BAI). Results: The current findings indicated there were non-significant statistical differences between both vaccinated and non-vaccinated groups which mean that both groups had similar demographic characteristics. The mean age for vaccinated group was (21.48±2.27) while for nonvaccinated was (21.31±2.38). Conclusion: The present study showed that COVID-19 vaccine is associated with a small change in menstrual cycle. The majority of vaccinated group had delay in the date of menstrual cycle, on the other hand, about two thirds of non-vaccinated and about three quarters of vaccinated group had between 9 and 12 spontaneous menstrual cycles per year. So study recommended: Further studies are needed to determine an association between the Covid-19 vaccine and menstrual changes.