We have previously observed impaired progesterone accumulation in vitro in response to human chorionic gonadotropin (hCG) by cells pretreated in vivo with a gonadotropin releasing hormone analog (GnRH-a). The present study was conducted in order to evaluate different protocols for GnRH-a in in vitro fertilization (IVF), employing two different available analogs. Granulosa-luteal cells were collected at ovum pick-up and stimulated with hCG. Buserelin (Bus) was employed as long (Bus-L) and short (Bus-S) protocol, and Leuprolide (Leu) was also used as long (Leu-L) and short (Leu-S) protocol. Progesterone accumulation in vitro was compared with cells treated with clomiphene citrate (CC) and gonadotropins. Maximal progesterone production was observed on culture day 6 using Bus-L in comparison to day 4 when clomiphene citrate was employed. While Leu-S showed a similar pattern of progesterone accumulation to clomiphene citrate, Leu-L and Bus-S had an intermediate pattern. The response to hCG was maximal on day 4 for the clomiphene citrate- and Leu-S-treated cells, while the rest of the protocols had a peak on day 6. In addition, hCG consistently stimulated progesterone production in all protocols except in Bus-L. These results confirm an altered progesterone accumulation in vitro when GnRH-a are used. The effect seems to be more evident in long protocols, especially when buserelin is used, suggesting a higher accumulation of the analog in follicular fluid.