An intense interest exists internationally in investigating in vitro procedures for the maturation, fertilization, and culture of immature oocytes from domestic mammalian species. In cattle, in vitro production of embryos is established as a commercial enterprise that includes the salvage of genetics from infertile females, as well as large-scale embryo production from slaughterhouse material. Ultrasound-guided aspiration of immature oocytes from cattle and buffalo on a twice-weekly basis has proven to be a highly effective technique. Immature oocytes also can be removed efficiently from horses by ultrasound-guided aspiration or from pigs, sheep, and goats by laparotomy or laparoscopy. In vitro maturation has been developed most efficiently for cattle, sheep, and goats, with a lower success rate for pigs and horses. Also, cattle, sheep, and goats have had the highest success rates with a variety of capacitation procedures using frozen-thawed semen. Success with other species varies, with a high degree of polyspermy characterizing in vitro fertilization in pigs and with a very low level of success in the horse. The zygotes resulting from in vitro matured and fertilized oocytes of cattle, buffalo, pigs, sheep, and goats have been successfully cultured to the blastocyst stage in a variety of in vitro systems. In contrast, there are no reports of horse blastocysts developing exclusively from in vitro procedures. In vitro embryos have been shown to differ from in vivo embryos with respect to morphology, cell counts, inner cell mass-to-trophoblast cell ratio, density, metabolism, osmotic behavior, and zonal properties. Survival of frozen-thawed in vitro embryos and pregnancy rates following transfer are generally lower than those of in vivo embryos. The number of offspring resulting from the transfer of in vitro embryos ranges from thousands in cattle to reports of only two in horses. In sheep and cattle, increased length of gestation, elevated perinatal losses, and larger-than-normal offspring resulting from in vitro embryos are reported widely. There is evidence that in vitro fertilization may prove useful in predicting the in vivo fertility of bulls. In vitro technology is an essential part of the growing fields of embryo cloning and the production of transgenic domestic species.