To explore the prevalence of dysmenorrhea among senior high school girls in Perth, Western Australia, its impact on school, sporting, and social activities, students' management strategies, and their knowledge of available treatment. A total of 388 female students in Grades 11 and 12 at three metropolitan secondary schools completed an anonymous questionnaire administered during class time. The following definition of dysmenorrhoea was used: any type of pain or discomfort associated with menstrual periods including cramps, nausea, and headaches. The reported prevalence of dysmenorrhea among these girls was 80%; 53% of those girls with dysmenorrhea reported that it limited their activities. In particular, 37% said that dysmenorrhea affected their school activities. The most common medication used by those reporting dysmenorrhea was simple analgesics (53%), followed by nonsteroidal anti-inflammatory drugs (NSAIDs), used by 42%. More than a quarter of respondents (27%) were unaware that NSAIDs were a possible treatment option for dysmenorrhea. The prevalence and impact of dysmenorrhea on Grade 11 and 12 girls is high, and they lack knowledge of and experience with effective treatment. Health education measures are needed in this area to prevent unnecessary suffering and interruption to school routine.