Genetic selection in heat tolerance is an original alternative to available techniques used to attenuate the effects of high temperatures on pig performance. Several methods can conduce to genetic improvement in heat tolerance (inbreeding or crossbreeding). To establish whether higher heat tolerance can be achieved by selecting more heat-tolerant animals, genetic variation of thermoregulation traits and its relationships with production traits must be better understood. It is significant that little references were available on genetic variation for heat tolerance in pig which contrasts with other species like ruminants or chickens.