Gamete intra-Fallopian transfer (GIFT) is the most important treatment method for infertile couples that has been developed since in-vitro fertilization and embryo transfer (IVF/ET) became available. Analysis of the data of 1071 first GIFT procedures is presented and the predominant factors affecting success are discussed. An overall pregnancy rate of 33.6% was achieved in this group of patients who were unselected in relation to age, number of oocytes transferred, quality of sperm and response to ovulation induction. The success of GIFT is dependent upon the number and quality of oocytes transferred and upon the quality of the sperm. Pregnancy occurred in 21.4% of patients receiving up to four oocytes compared with 40.3% in whom five or more were transferred. Multiple pregnancy rates however were 17.3% in the first group and 32.3% in the second group. Age is a major factor influencing the chances of success with patients less than 30 years of age achieving a 40.2% pregnancy rate reducing to 19.2% in the over 40 group. Conversely the spontaneous abortion rate increased from 23.4% in the under 30 group to 48.6% in those over 40 years of age. No pregnancies were achieved when sperm motility was less than 20% in the original specimen, whereas pregnancy rates of up to 20% resulted when sperm density was below 10 million. The overall results of this study show comparable success rates for different causes of infertility and that there is a definite association between the outcome of treatment and the number and quality of gametes transferred. A philosophy of flexibility in the treatment of infertile couples is advocated.