Menstruation is the beginning of a woman's puberty period where in menstruation there is regular decay of the endometrial layer. This occurs due to complex interactions between the hormone system and several organs of the body, namely the hypothalamus, pituitary, ovaries, and uterus. There are several indicators that can affect the menstrual cycle, namely body mass, anxiety levels, intensity of physical activity, dietary behavior, environmental exposure and work conditions. Physical activity with heavy intensity can affect reproductive hormones, thus affecting the irregular menstrual cycle. The purpose of this study was to determine the effect of physical activity on the menstrual cycle of female students of UIN North Sumatra in 2023. Research methods used quantitative methods with quantitative descriptive analysis through a cross-sectional approach. Data were analyzed by univariate test and chi-square test. The instrument of this research is google form. The results obtained from this study were that there was a significant relationship between physical activity and the menstrual cycle because based on the results of the chi-square test, the p-value was 0.010 <0.05. In addition, 47.5% of female students with irregular menstrual cycles and as many as 52.5% were regular. The conclusion that can be drawn is that the intensity of physical activity of female students of UIN North Sumatra 2023 can affect the menstrual cycle itself.