Background. A prospective randomised controlled trial comparing gamete intrafallopian transfer (GIFT) with intrauterine insemination (IUI) was undertaken at the Fertility and Reproductive Biology Unit of the Department of Obstetrics and Gynaecology, Tygerberg Hospital, between July 1999 and June 2000. Method. Eighty-five women were included in the study and were randomly allocated between the two groups after routine infertility investigations, 41 women to IUI and 44 women to GIFT. A combination of clomiphene citrate and human menopausal gonadotropin was administered to both groups to achieve ovulation. Results. Six (13.6%) of the 44 cycles in the IUI group and 24 (53.3%) of the 45 cycles in the GIFT group achieved conception. The mean number of cycles needed to achieve pregnancy in IUI was 7.3 (44/6) and in GIFT was 2.05 (45/24). The ongoing pregnancy rate of GIFT was 39.7% more effective than that of IUI (p=0.0001.The total ongoing pregnancy rate of GIFT was 30.8% superior to that of IUI (p=0.0021). When 2 follicles were obtained in an IUI cycle, GIFT was 41.6% more effective (p=0.0024), and when more than 2 follicles were obtained, GIFT was 28.3% more effective (p=0.0265). Conclusions. The number of mature follicles significantly increased the chance of pregnancy with IUI. In comparing the number of cycles needed to achieve a pregnancy, 1 GIFT cycle is equivalent to more than 3 IUI cycles. It is important to note that 4 IUI cycles will give equivalent or even better results if 2 - 3 follicles are recruited per cycle. In spite of the greater efficacy of GIFT, the authors conclude that at least 3 to 4 IUI cycles should be attempted before GIFT, on the basis that it is more cost effective and less invasive. South African Journal of Obstetrics and gynaecology Vol. 13 (3) 2007: pp. 104-109