Lead content of ovarian follicular fluid obtained from 23 women was determined by atomic absorption spectrophotometry. In an in vitro experiment the direct effect of lead on the morphology and on progesterone (P) production by cultured granulosa cells of six women was investigated. Follicular fluid and granulosa cells were obtained from follicular aspirates of women undergoing in vitro fertilization (IVF) and embryo transfer (ET). Granulosa cells were cultured for 48 h to form monolayers in the presence or absence of lead acetate (100-1,600 microM). The effect of the metal proved to be concentration dependent. While 100-400 microM lead had no effect on the integrity of the monolayer, concentrations as high as 800 microM or higher inhibited cell adhesion and induced detachment of cells. The lead levels found in follicular fluid were 11.29 +/- 1.38 microg/L (0.056 +/- 0.007 microM). With lead in vitro at 1,600 microM (331.5 mg/L) there resulted a significant decrease in P production by granulosa cells. This concentration is very much higher than that measured in follicular fluid of IVF/ET patients, specifically nonexposed to lead, and even higher than mean blood levels reported by others in high exposure groups. In conclusion, lead seems not to exert a specific effect on the steroidogenesis by cultured human granulosa cells. Therefore, the lead levels measured in the ovarian follicular fluid seem not to pose a hazard with respect to progesterone secretion by the ovary.