The purpose of this study was to evaluate the luteal function, as affected by gonadotropin, through the examination of luteinized human granulosa cells in culture. These cells, obtained from IVF patients stimulated by hMG (human menopausal gonadotropin)/hCG (human chorionic gonadotropin), produced estrogen and progesterone under the effects of hCG and FSH (follicle stimulating hormone). This effect was clearly demonstrated in this study. The culture medium was renewed every 48 hours. Hormones, including androstenedione (100 ng/mL), FSH (100 ng/mL), and hCG (11 U/mL), were added to the culture medium. The levels of estradiol and progesterone were measured at each change of the culture medium. Study I showed, only on days 4-6, that the addition of FSH (100 ng/mL) produced a significant increase in the estradiol and progesterone production (p < 0.05), in either the presence or absence of androstenedione. The effect did not occur on days 0-2, or on days 2-4. In study II, FSH was added to the medium on a different schedule (days 2-4 and days 4-6). Again, only on days 4-6 was a positive result obtained, as in study I (p < 0.05), but no significant response was noted on days 2-4. Study III showed that the addition of hCG on days 2-4 produced a 10% increase (p < 0.05) in estradiol production and a 50% increase in progesterone (p < 0.01). On the other hand, on days 4-6, there was a 40% increase in estradiol and a 200% increase in progesterone (p < 0.01). Again, no significant response to hCG was obtained on days 0-2.(ABSTRACT TRUNCATED AT 250 WORDS)