OBJECTIVE The polycystic ovarian syndrome is frequently associated with human infertility and is a partially characterized syndrome of unknown aetiology. The aim of this study was to describe the functional integrity of granulosa cells from polycystic ovaries.PATIENTS Follicular aspirates were collected from polycystic ovaries of ovulatory (n = 24) and anovulatory (n = 7) patients. Follicular aspirates were also collected from normal ovaries of untreated (n = 24) and superovulated (n = 10) subjects. All patients were enrolled for the recovery of their oocytes forin vitromaturation and fertilization.MEASUREMENTS FSH receptors and apoptosis were measured in the granulosa cells of the different patients. FSH‐stimulated oestradiol and LH‐stimulated progesterone production by granulosa cells of the different patients were also measured.RESULTS The binding of125I‐labelled human recombinant FSH to granulosa cells from anovulatory subjects with polycystic ovaries was significantly higher than that found in granulosa cells from normal (180%) and superovulated (163%) ovaries. However, the ligand binding to granulosa cells from ovulatory subjects with polycystic ovaries was not significantly higher than that found in normal granulosa cells. Also, granulosa cells obtained from anovulatory subjects with polycystic ovaries cultured with FSH produced more oestradiol than normal granulosa cells but oestradiol production was similar to that of granulosa cells from superovulated ovaries (mean ± SEM, 244.94 ± 22.02, 24.23 ± 2.92, 211.87 ± 50.39 nmol/l/24 h, respectively). Flow cytometric analysis showed that the proportions of viable and apoptotic granulosa cells (mean ± SDM, 70 ± 5 and 7 ± 1%, respectively) were similar in normal subjects and in those with polycystic ovaries.CONCLUSION We conclude that most of the granulosa cells of polycystic ovaries are healthy and non‐apoptotic, expressing high levels of FSH receptors and highly responsive to this hormone in culture. These data provide direct e