Introduction & Objective: Premenstrual dysphoric disorder is considered as a mood disorders that 30 to 80 percent of women have at least mild symptoms and that 2 to 10 percent have severe symptoms of this disorder. The exact cause of this disorder is not clear, but according to one of the most common theories, it seems to be the higher level of estrogen to progesterone in affected women. The symptoms of this disorder include: hopelessness, agitation, emotional disturbance, anger and physical complaints (headache, breast tenderness and edema). The symptoms cause clinically significant impairment in social, occupational or interpersonal functioning. The purpose of this study was evaluation of the prevalence of premenstrual dysphoric disorder in Hamadan high school girls, in 2003.

Materials & Methods: This was a descriptive-analytic cross-sectional study. Maximum sampling error was considered to be as 5% and confidence interval was 95%. 384 educating high school girls from Hamadan were selected randomly and were asked by questionnaires that were designed on the basis of premenstrual dysphoric disorder criteria, according to psychiatric references. Data were statistically analyzed by SPSS 10 using c² test.

Results: From 384 studied girls, 172 subjects (44.5%) were diagnosed with premenstrual dysphoric disorder which 18 cases of them were suspicious to have other disorder such as depression. 102 patients among affected girls (59.3%) were diagnosed during the first year of beginning menstruation. Duration of symptoms of premenstrual dysphoric disorder was more than three days in 20% of cases. Mood, behavioral and physical symptoms were coexisted in 71.5%, 61% and 73.2% of the girls with premenstrual dysphoric disorder respectively, and these associations were statistically significant (p<0.01).

Conclusion: Prevalence of premenstrual dysphoric disorder in Hamadan high school girls was near to its prevalence in general population (40%). More than two thirds (2/3) of the patients had also three groups mood, behavioral and physical symptoms together.