The clinical efficacy of conventional and advanced methods of treatment was assessed in 814 couples with infertility due to a male factor. The monthly and effective cumulative rate of ongoing or term pregnancies was calculated during 4712 couple-months. Treatment of varicocele by transcatheter embolization, resulting in 3.9% pregnancies per cycle and an effective cumulative pregnancy rate of 41% after 1 year, is more effective than counselling and timed intercourse (9% pregnancies after 12 months). Intrauterine insemination (IUI) of washed spermatozoa produced 17% pregnancies in the initial 4 months, but the success rate of the subsequent cycles (1.7% per cycle) was not different from that of the controls. In vitro fertilization (IVF) resulted in 16% pregnancies per attempt, but the effective cumulative pregnancy rate was only 31% in 12 months due to the long interval between treatment attempts and the high drop-out rate. With subzonal microinjection of sperm, the fertilization rate was higher (71%) than with regular IVF (29%) but both the pregnancy rate per attempt (9%) and the effective cumulative pregnancy rate (17% after 12 months) were low. The 10th percentile of sperm characteristics (cut-off values) of successful cases showed intrauterine insemination to be advantageous in cases with a lower percentage of spermatozoa with progressive motility (9%) than in the controls (15%). The cut-off value of sperm morphology in IVF (4%) is lower than that of IUI (8%) and of the controls (9%), but higher than that of subzonal insemination (1%). Treatment strategy must be defined selecting or combining conventional and assisted reproductive technology for each individual couple with male factor infertility.