Comparative tests were conducted in an environment–controlled farrowing room [21C (70F)] to determine the choice of mat heat vs. lamp heat by piglets in farrowing crates. Two widened farrowing crates [2.40 Ü 2.13 m (8 Ü 7 ft] were used, each equipped with two double–size heat mats [0.6 Ü 1.2 m (2 Ü 4 ft) 120–W capacity each]. One mat was powered to provide the localized heat, while the other simply served as a floor mat with a 175–W heat lamp suspended 76 cm (30 in.) above it for localized heat. Both heat sources were placed along one side of the sow; hence one mat was closer to the posterior of the sow than the other. The heat source located near the posterior of the sow was clearly preferred by piglets regardless of its type. Lamp heat was used significantly more than mat heat for the first two days after birth. Surface temperatures of piglets and heat sources were quantified. In particular, surface temperature of piglets resting under the heat lamp decreased linearly with the distance between the piglets and the center of the heat source, ranging from 39.4 to 33.4C (103 to 92F).