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. STUDY DESIGN: 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. CONCLUSION: 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.