Introduction : A collection of physical and psychological symptoms associate with the menstrual cycle in women during childbearing age is called Premenstrual Syndrome. The aim of this study was to compare the effects of Omega-3 and Perforan on severity mood symptoms in Premenstrual Syndrome.

  Methods : The study was a randomized, double blind, placebo- controlled trial, with three treatment- groups. The subjects of this study (150 students) were divided randomly into three groups include of Omega-3, Perforan group and placebo control group. The subjects took drugs during three subsequent cycles so that they took two capsules daily in the first cycle for one month and in the second and third cycles they took them from eight days before menstruation to two days after it and records the severity of the symptoms of her menstruation in the questionnaire of the symptoms .

  Results: The severity of premenstrual syndrome was lower in the treatment groups (Omega-3 and Perforan) than in the placebo group. Results showed that there was no statistically significant difference between three groups before the intervention (p=0.68). But severity of mood symptoms one, two and three months after use of omega-3 were (30.46, 32.79 and 24.06) and one, two and three months after use of perforn were ( 30.93, 31.80 and 23.64 respectively (p=0.001).

  Conclusion: Omega-3 and Perforan significantly reduce the severity mood symptoms of Premenstrual syndrome.