OBJECTIVE The purpose of this study was to evaluate the efficacy of intrauterine inseminations (IUI) as first line treatment of unexplained or male factor infertility. METHODS Retrospective analysis of 414 consecutive IUI treatment cycles in 124 couples with unexplained or male factor infertility. RESULTS In 414 cycles 25 pregnancies were achieved (6% pregnancy rate per cycle and 20% per couple respectively). 24 healthy babies were born (20 singletons and 2 twins) as a result of our treatment. There was no significant difference in ejaculate parameters of patients who achieved a pregnancy compared with patients who failed to do so. Lowest values at which pregnancies were achieved were 0.8 mill sperm/ml and 11% progressive motility after sperm processing and 8% normal morphology before semen preparation. CONCLUSIONS There is still a place for IUI as first line treatment for couples with unexplained or male factor infertility. Even in patients with moderate impairment of semen quality pregnancy rates up to 20% per couple can be achieved.