Five infertile women exposed to long-acting gonadotrophin-releasing hormone agonist (GnRHa) during early pregnancy were studied to assess the risks of embryotoxicity on the outcome of their pregnancies. All the patients were diagnosed as stage 3-4 endometriosis following laparoscopy, Long-acting GnRHa (3.75 mg) was given in the first 3 days of their preceding menstrual period. Four of the five patients had two GnRHa injections and the last patient had three GnRHa injections. All patients were advised to use a barrier contraception (condoms) throughout the treatment period. Since all complained of no bleeding following the initial injections, human chorionic gonadotrophin (beta-HCG) concentrations were tested in order to rule out any pregnancy. Ultrasonographic examinations were commenced routinely and all patients had amniocentesis at 16-18 weeks gestational age. Genetic analysis revealed a normal karyotype in all fetuses. All five pregnancies progressed to term without complication, and normal healthy infants were delivered. Although there are still no clear answers concerning teratogenic and hormonal effects of GnRHa exposure in pregnancy, our data may suggest that luteal function, genetic structure and pregnancy outcome are not adversely affected by GnRHa, Since possible subtle effects on fetal endocrine organs cannot be disregarded, close monitoring is still needed in GnRHa-exposed pregnancies.