The aim of this study was to determine if follicle stimulating hormone receptor and luteinizing hormone receptor (FSH-R and LH-R) expression is altered on granulosa cells (GC) of women with low oestradiol responses to FSH. Cells were obtained from mature follicles (>17 mm) following controlled ovarian stimulation. For comparison, chinese hamster ovary (CHO) cells transfected with FSH-R or LH-R were also assessed. FSH-R and LH-R expression were detected by flow cytometry. Receptors were labelled with FSH-R antibodies, or with excess FSH or human chorionic gonadotrophin (HCG) and anti-FSH or HCG antibodies, and compared to multiple controls. Receptor expression on GCs was more heterogeneous than on CHO cells. Gonadotrophin receptor levels on GCs were not correlated with the number of FSH ampoules administered or peak oestradiol response. Low and normal response groups were defined using a ratio of peak oestradiol/number of FSH ampoules. FSH receptor expression was not different on GCs from low and normal responders. However, LH-R expression was higher on GCs of low responders compared to those of normal responders (P = 0.04 ) suggesting a trend to more advanced luteinization. Access of hormone to follicles was not reduced in low responders. Thus, differences in gonadotrophin receptor expression, hormone binding, and access of hormones to follicles do not appear to account for low oestradiol responses to FSH.