OBJECTIVE To investigate the follicle development and pregnancy in clomiphene citrate-resistant patients with polycystic ovary syndrome (PCOS) after transvaginal follicular aspiration and gonadotropin administration. METHODS Seventeen clomiphene citrate-resistant patients with PCOS failed to gonadotropin treatment associated with ovarian hyperstimulation syndrome (OHSS). They are anovulatory infertility with normal tubal and husbands' sperm condition. In this treatment regimen, all patients was administered with gonadotropin from day 5 of menstrual cycle (or withdrawal bleeding) and were asked to undergo ultrasound-guided transvaginal follicular aspirations for 5 days later. Only one or two follicles for every ovary were remained and gonadotropin administration was continued. A follicle development, ovulation rate, pregnancy rate and sex hormone were monitored. RESULTS Fifteen of the 17 patients experienced dominant follicles development and ovulation. 9 of them with one (52.9%), 4 with two (23.5%) and 2 with three (11.8%) dominant follicles ovulated and pregnancy occurred in 7 patients (41.2%). All of pregnancy are singleton. CONCLUSIONS A single follicle development and singleton pregnancy can be realized in clomiphene citrate-resistant PCOS patients by combined ultrasound-guided transvaginal follicular asperation with gonadotropin administration.