Abstract: Dysmenorrhea is a common problem in young women. Although, dysmenorrhea is not life threatening, it can have adverse effects on quality of life. Various treatments are offered for dysmenorrheaincluding exercise and keep the body warm. This study examines dysmenorrea in female swimmers and non-swimmers. In this descriptive comparative trial, 200 female students who suffered from primary dysmenorrhea were recruited to the study at YAZD girls high school. They filled a questionnaire including demographic characteristics and the pain measurement chart (duration and severity). Then, they were divided intothree groups: low, moderate and severe dysmenorrhea groups. Data were analyzed and using t-student, chi-square and variance analysis tests in SPSS Software. The age of the students ranged 16±1.2 years old. The severity of pain was 7.3±1.3 in swimmer group and 7.8±1.5 in non swimmer group (p<0.001). The severity of dysmenorrhea was mild, moderate and severe, respectively in 58, 28 and 14% swimmers group and 9, 26 and 65% in non swimmer group. The mean of painful menstrual days in swimmers group 92% in first day, 5% in the first 2 days and 3% in 3 days and in non swimmers group 24% in first day, 54% in first 2 days, 15% in 3 days and 7% inall of days reported pain. Swim significantly reduces the duration and severity of pain in patients with primary dysmenorrhea is. It canbe used as an alternative treatment method in affected women.