The aim of this work was to compare the action of recombinant follicle stimulating hormone (rFSH) and urinary FSH (uFSH). Moreover we aimed to compare the secretory efficiency of continuous versus pulsatile stimulation by rFSH in superfused human luteal cells. Progesterone concentration was measured in culture medium by radioimmunoassay. Action of rFSH and uFSH was compared in static cultures of human granulosa cells at doses of 0.001-10 IU/ml. The secretory efficiency of both rFSH and uFSH was found to be similar in a defined range of concentrations (0.001-0.3 IU/ml). At concentrations of 1 and 10 IU/ml, the action of uFSH was significantly more potent than rFSH, up to 139% (P < 0.01) and 133% (P < 0.01) respectively. A concentration of 0.3 IU/ml of rFSH was most potent in static cultures, and evoked progesterone release up to 80 mg/ml. For a stimulation period of up to 4 h, the action of rFSH and uFSH in human granulosa cells was time-dependent and differences between them were not significant. Irregularities were observed at > 4 h stimulation time. In another experiment, in superfused human granulosa cells, we showed that the stimulatory effectiveness of pulsatile rFSH administration (time interval 60 min, application time 10 min) was greater for progesterone release (3973 ng of progesterone/1 IU rFSH) than was continuous administration (848 ng of progesterone/1 IU rFSH). In conclusion, the secretory action of rFSH is similar to that of uFSH for defined times and doses. Moreover, pulsatile rFSH administration is more efficient at stimulating the release of progesterone than continuous administration.