The role of prostaglandins (PGs) in dysmenorrhea of endometriosis is poorly understood. The relationship between dysmenorrheic severity and prostaglandin production was investigated in endometriosis. Slices of normal myometrium, adenomyosis, normal ovary and endometrial cyst were incubated. 6-Keto-PGF1 alpha (a metabolite of PGI2), TXB2 (a metabolite of TXA2), PGF2 alpha, and PGE2 concentrations of the incubation medium were measured by RIA. The results showed that 6-keto-PGF1 alpha production in adenomyosis and endometrial cyst were significantly higher than those in normal myometrium and ovary. A direct relationship between the degree of dysmenorrheic severity and PGs production in tissue in endometriosis was observed.