Clinical pregnancies have been initiated by ZIFT using zygotes produced by reinsemination of oocytes with donor sperm ("donor rescue") after an initial 15- to 20-hour exposure to husband's sperm. A total of 54 oocytes from four couples experiencing failed fertilization by husband's sperm were reinseminated with donor sperm, resulting in 38 zygotes (70.4% fertilization). Four zygotes were transferred during ZIFT in each case and resulted in two (50%) continuing pregnancies. Additional zygotes from donor reinsemination were cryopreserved for each couple. Donor rescue expands the utility of ZIFT as a treatment for male factor infertility.