To evaluate the effectiveness of GnRH agonist for the treatment of uterine myoma as a cause of infertility, fourteen women were recruited to the study. The patients were treated with a delayed-release formulation of D-$Trp^6$-LHRH in biodegradable microcapsules(Decapeptyl-CR), administered intramuscularly at four week intervals for a period of six monthes. The first injection was given on day 21 of the cycle. Serum estradiol levels fell significantly to the mean value of 257.7pgjml 4 weeks after the first injection. Eleven patients in fourteen treated patients had a reduction in the size of uterine myoma as assessed by ultrasonography, two patients had no change of size and one patient had a increase of size. After the first or second injection, all patients became amenorrheic, then resumption of menstruation ocurred at 12 to 14 weeks after the last injection. Common side effects were hot flush, sweating and dyspareunia, whitch were acceptale. In Eleven patients who had a reduction in the size of uterine myoma by treatment with a delayed- release formulation of D-$Trp^6$-LHRH(Decapeptyl-CR), after above treatment with GnRH agonist, then four patients were treated with myomectomy, three patients had pregnancy and full term delivered by Cesarean section. These data suggest that administration of a delayed-release formulation of a GnRH agonist can be a worthwhile and convenient approach to the medical treatment of uterine myoma as a cause of infertility.