Small multiple follicles (> 9) and enlarged ovarian volume (> 6.8 ml) were the most prominent transvaginal ultrasonographic features of ovaries in Clomiphene Citrate nonresponsive patients with polycystic ovarian syndrome. Higher levels of Testosterone, luteinizing hormone and significantly higher number of small follicles were associated with lack of Clomiphene Citrate response. These ultrasonographic features and laboratory assays could be clinically useful for distinguishing better the Clomiphene Citrate nonresponders from responders.