Although dysmenorrhea is a leading cause of gynecologic complaints among adolescents, its pathogenesis is incompletely understood. The purpose of this study was to determine the role of prostaglandins and leukotrienes in the pathogenesis of dysmenorrhea. Twenty patients with dysmenorrhea aged 16.2+/-1.2 years and 20 healthy age-matched controls with eumenorrhea (absence of pain during menstruation) were included in the study. Serial measurements of serum PGF2alpha and urinary LTE4 levels during the menstrual cycle were obtained; serum progesterone was measured and ultrasonographic evaluations were made. LTE4 and PGF2alpha levels decreased on the third day and recovered on the 10th day of the menstrual cycle in both groups. Urinary LTE4 levels were higher in the control group than in the patient group on the 1st, 3rd and 10th days of the cycle (p<0.05 for each). This study suggests that there is a distinct pattern of leukotriene production during the menstrual cycle, but the changes in the systemic level are not responsible for their role in the pathogenesis of dysmenorrhea. Further studies at the local level in the target organ are necessary to elucidate the role of the lipid mediators in the pathogenesis of dysmenorrhea.