A GIFT cycle involves harvesting the oocytes (eggs from the patient's ovaries). A few mature oocytes are mixed with the partner's sperm and immediately placed back in the fallopian tubes. Therefore, fertilization and embryo development take place in the woman's body. In a ZIFT cycle, the oocytes are fertilized in the laboratory and 12-16 hours later some fertilized eggs (zygotes) are replaced into the fallopian tubes.

Women with normal fallopian tubes, absence of severe pelvic adhesions, sperm antibodies, no history of ectopic pregnancies, and whose male partners produce sperm with fertilizing ability may be candidates for GIFT or ZIFT.