To determine the prognostic factors such as age, diagnosis, number of cycle attempts and semen parameters on the pregnancy rate of controlled ovarian hyperstimulation (COH) /intrauterine insemination (IUI). Three hundred and seventeen women who underwent 507 consecutive COH/IUI cycles were recruited from 1st January 2002 to 31st December 2005 inclusively. This retrospective study was done in University Malaya Medical Centre, a tertiary care academic centre. The main outcome measure was pregnancy rate according to age, infertility diagnosis, duration of infertility, semen parameters, and the number of treatment cycles. The overall pregnancy rates were 16.9% per cycle and 25.9% per couple. Pregnancy rates decreased with advancing maternal age. Pregnancy rate was also significantly lower in patient with postwash total motile sperm count (TMSC) < or = 20 million/ml compared to those with TMSC >20 million/ml. The cumulative pregnancy rates varied greatly by diagnosis from 16% for patients with male factor infertility to 60% for patients with ovulatory disorder. Pregnancies among patients with male infertility, tubal factors infertility and endometriosis were achieved during the first three cycles. There is a clear age-related decline in fecundity associated with COH/IUI treatment. Women of > 40 years old, couple with postwash TMSC < or = 20 million/ml, severe endometriosis and tubal factors have a particularly poor prognosis.