The influence of different oral contraceptives on the prevalence and severity of dysmenorrhea was investigated in a representative sample of 19-year-old women from an urban Swedish population. The prevalence and severity of dysmenorrhea were significantly (p less than 0.01) reduced amongst users of progestogen-dominated oral contraceptives compared to a control group of women who used neither oral contraceptives nor an intrauterine device. However, there was no significant difference in the prevalence and severity of dysmenorrhea between users of oral contraceptives with low progestogen activity and the same control group. Thus, the relative progestogen activity of the oral contraceptive used appears to be of importance for the effective treatment of dysmenorrhea. Possible reasons for the superior therapeutic efficacy of progestogen-dominated oral contraceptives are discussed. Further studies are, however, necessary to evaluate the importance of the progestogen activity of oral contraceptives in the treatment of dysmenorrhea.