Ten adolescents with primary dysmenorrhea (PD) were treated with the oral contraceptive (OC) Lyndiol 2.5 mg (R) for one cycle. The levels of PGF2 alpha, PGE2 and the metabolites of PGI2 and TXA2: 6-keto-PGF1 alpha and TXB2 were tested by a radioimmunoassay method during the 1st and 23rd day of the pre-treatment cycle (PrTC), the 23rd day of treatment (TC) and the 1st day of the post-treatment cycle (PoTC). The ratios PGF2 alpha/PGE2 and TXB2/6-keto-PGF1 alpha were also tested and compared during the above-mentioned days. Analytical comparison was made, for each Prostaglandin (PG) separately, between the 1st day of the PrTC and PoTC as well as the 23rd day of the PrTC and TC, respectively. All PG levels during TC and PoTC were found significantly lower, compared to those of the PrTC respectively. With regard to the ratios mentioned above, no statistically significant differences were found on the same days and cycles as previously stated. The reduction of the PG levels in PD patients after treatment with oral contraceptives, together with an improvement of the clinical findings of the disease, support the theory that oral contraceptives can be used for the treatment of PD cases, especially for those adolescents who also desire a contraceptive method.