Intrauterine insemination (IUI) remains a therapeutic option within means of the majority of infertile couples in Malaysia. Therefore additional information on predictors of IUI success in the local context would provide a more concrete basis for counseling patients on expectations and treatment options. A retrospective analysis of 297 couples who underwent 445 IUI cycles from Jan 2005-Mar 2006 was undertaken. Four fifths were Malay with a mean paternal and maternal age of 35.53 +/- 5.82 (range 24-59) and 33.02 +/- 4.69 (range 21-46) years respectively. Causes of infertility were idiopathic (50%), endometriosis (17%) and anovulation/polycystic ovarian syndrome (15%). Almost 10% were oligoastenoteratozoospermic with another 23% oligozoospermic or astenozoospermic. Combined male and female factors occurred in 26%. A pregnancy rate (PR) of 9.4% per cycle; 14.1% per couple with a cumulative PR of 36.7% per 4 cycles was achieved. Those who became pregnant were significantly younger (31.29 +/- 4.43 vs. 33.21 +/- 4.68 years, p = 0.011) and had more follicles (13.95 +/- 9.72 vs. 11.43 +/- 6.67, p = 0.029) at the time of insemination. PR depreciated with maternal age and semen quality. Maternal and paternal age was inversely correlated to the number of follicles recruited (r = -0.30, p < 0.0005) and progressive sperm motility (r = -0.125, p = 0.013) respectively.