['To explore the importance of follicle-stimulating hormone receptor (FSHR) in granulosa cells in the ovarian response to gonadotropin stimulation.', 'Prospective study.', "A women's hospital in China.", 'One hundred infertile women undergoing ovarian stimulation with recombinant follicle-stimulating hormone (rFSH).', 'These women were divided into three groups: poor, moderate, and high responders, according to the number of follicles with diameter >/=14 mm. The FSHR expression at both mRNA and protein levels was determined by either reverse transcription-polymerase chain reaction or Western blot in granulosa cells. E(2) concentrations in serum and FSH levels in serum/follicular fluid (FF) were measured by electrochemiluminescence immunoassay.', 'Relative expression of mRNA and protein of FSHR in granulosa cells, serum E(2), FSH level in serum and FF, and the number of mature follicles.', 'The expression of FSHR, at both the mRNA and protein levels, was significantly different among the three groups, with the lowest expression in the poor responders. The level of FSHR protein was positively correlated with the peak level of serum E(2) and the number of mature oocytes. FSH levels in FF and the dosage of rFSH used were significantly different among the three groups, with the highest values in the poor responders.'] Is poor ovarian response to gonadotropin stimulation associated with low expression of follicle-stimulating hormone receptor in granulosa cells?