Heat stress causes infertility in farm animals and represents a major source of economic loss for farmers. The decrease in farm animal fertility is caused by elevated body temperature that negatively influences events that are essential to the reproductive process. For example, ovarian and testicular function, oocyte and sperm health, estrous expression, uterine function and early embryonic development are inhibited when animals are heat-stressed. Farmers can employ a variety of approaches to improve reproduction during heat stress. These approaches usually involve modifying the environment (i.e., attempting to cool farm animals during reproduction), modifying the genetics of the farm animal (i.e., breeding for heat tolerance) or intensifying reproductive management during periods of heat stress. Molecular analyses of heat-stressed tissues may elucidate control points for improving reproductive endpoints. This review will examine the impact of heat stress on animal agriculture as well as the mechanisms through which heat stress affects reproductive physiology. Novel methods for understanding and managing reproduction during periods of heat stress will also be presented.