Direct intraperitoneal or intrauterine insemination in combination with superovulation was used randomly as the treatment of infertility that was unexplained or due to male subfertility or mild endometriosis in 124 couples during 326 cycles. The pregnancy rate per couple was 24% in the direct intraperitoneal insemination group and 31% in the IUI group. The difference was not significant. The pregnancy rates with both treatments were significantly higher than those seen during the 326 control cycles of the same couples (1.1% and 0.6%).