The objective of the researchers of this study is to evaluate the effect of the Carbohydrate Quality Index (CQI) in the diet of university students living in dormitories on the severity of premenstrual symptoms. The researchers applied a survey to the students, including questions about their sociodemographic characteristics and eating habits, Food Frequency Questionnaire (FFQ), and Premenstrual Symptom Scale (PMSS). A total of 606 female students were included as participants in the study. CQI value of students with PMS was found to be lower (p < 0.05). It was observed that increasing the CQI could reduce the PMSS score [β (-0.228 (0.18-0.007) 95%CI] (p < 0.05).