A short suppression regimen with daily 0.5 mg leuprolide commencing the first day of in vitro fertilization (IVF) cycles was evaluated in 10 women who previously underwent similar IVF cycle without suppression. Induction of ovulation, oocyte retrieval, incubation, and embryo transfer were similar in all the cycles. Assessment included the amount of human menopausal gonadotropin (hMG) used, length of stimulation, serum estradiol and luteinizing hormone (LH) levels, number of oocytes retrieved and their quality, cleavage rate, and number of embryos. The results showed that when leuprolide was used, no endogenous LH surge was detected, and there was a significant increase in hMG injected, from 19.0 +/- 5.8 to 34.4 +/- 17 ampoules, and in estradiol levels, from 1276 +/- 470 to 2618 +/- 1084 pg/ml (mean +/- SD). In addition, there was an increase in the total oocytes retrieved from 54 to 94, their cleavage rate from 59 to 86%, and the number of embryos from 24 to 70 in the suppressed cycle. No deleterious effects were observed and there were two pregnancies in this group.