A high rate of ovarian multifollicular development and resulting multiple pregnancy remains the main problem of ovulation induction with human menopausal gonadotropins. The aim of this study was to examine a possible correlation between the number and size of ovarian follicles at the time of human chorionic gonadotropin (hCG) administration and to find parameters that can predict the occurrence of multiple pregnancies. Sixty-eight intrauterine pregnancies, 53 singletons and 15 multiple pregnancies in 51 patients, were included in this study. We found no significant difference in the mean estradiol levels, the total number of pre-ovulatory follicles, or the mean number of large, intermediate or small follicles at the time of hCG administration between women who had singleton pregnancies and those with multiple pregnancies. Our study demonstrates that estradiol levels and ovarian ultrasonography do not provide criteria for the prediction of the occurrence of multiple pregnancies in menotropin cycles.