Fifty infertile women with the polycystic ovary syndrome (PCOS) were treated for 66 cycles with low-dose FSH stimulation starting with 75 IU FSH for two weeks before eventual stepwise increases in the gonadotropin dose occurred. An unifollicular response was observed in 35 (53%) cycles and in 20 (30%) cycles there were two-three mature follicles. A multifollicular response (> 3 mature follicles) resulted in 11 (17%) cycles. One of the 66 cycles was complicated with the ovarian hyperstimulation syndrome. Twelve (22%) pregnancies were obtained following 55 completed cycles. All ongoing pregnancies were singleton gestations. The obese PCOS women required a longer period of stimulation and a higher amount of gonadotropin to achieve follicular maturation. However, there was no difference in cycle cancellation or pregnancy rate between obese and non-obese PCOS women. Thus low-dose FSH administration seems a safe stimulation regimen with a satisfactory conception rate in PCOS women.