其他摘要：Background Premenstrual syndrome (PMS) is a combination of physical, psychological and emotional symptoms that occur periodically before menstruation and disappear with the onset of menstruation. There are some therapeutic methods mostly according to the clinical trials that reduce the prevalence and intensity of symptoms of PMS by unknown mechanisms. This study aimed to investigate the effects of Calcium and vitamin B1 on Premenstrual syndrome among female students. Materials and Methods: This is a triple-blind clinical trial conducted on 210 female students living in dormitories of Ilam University of Medical Sciences who had PMS. PMS symptoms questionnaire was used to investigate the symptoms. Participants were assigned in 3 groups of 70 people with the following regimen: group 1 received one pill containing 100 milligrams vitamin B1, group 2 received Calcium pills and group 3 received placebo. The participants in all groups took medicines for 2 months and then reported the intensity of their symptoms by the questionnaire. The collected data was analyzed by descriptive and inferential statistics, using SPSS-16. Results: In groups receiving vitamin B1, Calcium and placebo, the intensity of physical and psychological symptoms as well as general symptoms of PMS had a remarkable reduction (P
