The purpose of this study is to determine the changes in skin temperature of hyperbilirubinemic term newborns under conventional and fiberoptic phototherapy. The study included a group of 41 hyperbilirubinemic, but otherwise healthy, term infants, all of appropriate size for gestational age. The study was devised to include two separate groups: group 1 of 21 infants (51.2%) received conventional phototherapy, and group 2 of 20 infants (48.8%) received fiberoptic phototherapy. In both groups the surface temperature on the forehead, abdomen, left leg and back was calculated by infrared radiation thermometer (Cyclops Compac 3, Minolta, Land, England). A ``Photo-Therapie 800 Heraeus'' unit (Drager, Lübeck, Germany) was used for conventional phototherapy (CPT). A ``Biliblanket PT system'' (Ohmeda, Louisville, KY) was used for fiberoptic phototherapy (FO-PT). In our study we did not find significant differences of skin temperature in the four areas examined in the two groups prior to phototherapy. During conventional phototherapy, mean values of skin temperature were found to be significantly higher than those found before phototherapy. During fibreoptic phototherapy no statistically significant temperature differences were found on the forehead, abdomen, leg, and back before and during phototherapy. Furthermore, a statistically significant increase in skin temperature was found during phototherapy on the forehead, abdomen, leg, and back in patients of group 1 with respect to patients of group 2. We demonstrated that fibreoptic phototherapy, in contrast to conventional phototherapy, does not induce a significant increase in skin temperature.