The efficacy of intrauterine insemination (IUI) for male or cervical factor by age of female partner was determined in a retrospective analysis. Patients who underwent IUI therapy for cervical and/or male factor (n = 281) were classified by age at first IUI cycle: <40 years (n = 232), > or =40 years (n = 49). The indication for IUI was cervical factor if a postcoital test failed to show sperm with good forward progression at time of mature follicle; male factor was diagnosed if the semen analysis demonstrated either low count, low motility, antisperm antibodies, or subnormal hypoosmotic swelling test. Intrauterine insemination was performed in either natural cycles or following ovarian stimulation for the treatment of anovulation or follicular maturation defects. Cumulative probability of ongoing pregnancy (viable at end of first trimester) following 3 cycles of IUI was evaluated. Cumulative probability of ongoing pregnancy following 3 cycles of IUI was 28.2% for the younger group and 0.0% for the older group. The age groups did not differ in terms of infertility history, use of ovarian stimulation, or baseline semen parameters. Thus, the treatment of male and/or cervical factor by IUI is ineffective for women > or =40 years.