BACKGROUND Rectal thermometry correlates with core temperature and represents the criterion standard of measuring temperatures in young children. However, it has numerous disadvantages, and thus, an alternative method of measuring temperature with similar agreement with the core temperature as rectal thermometry is desired. A new, noninvasive temporal artery (TA) thermometer synthesizes the skin surface and ambient temperatures to produce an arterial temperature. OBJECTIVE To examine the agreement between the TA and esophageal core thermometers, and to compare it with that between rectal and esophageal temperatures. METHODS In the present prospective, cross-sectional agreement study, intubated surgical outpatients younger than 18 years of age had temperatures measured with esophageal and rectal probes, and rectal electronic and TA thermometers. The agreement between esophageal versus rectal and TA thermometers was analyzed by intraclass correlation coefficients and by differences between esophageal versus TA and rectal temperatures with 95% CIs. The esophageal-rectal and esophageal-TA slopes were compared by Student's t test. RESULTS In 80 enrolled children, the intraclass correlation coefficients for the esophageal probe versus rectal probe, rectal electronic thermometer and TA thermometer were 0.91, 0.95 and 0.88, respectively. The mean esophageal-rectal difference was 0.00+/-0.18 degrees C and esophageal-TA difference was 0.14+/-0.20 degrees C. Linear regression analysis of the relation between esophageal probe versus rectal probe, rectal thermometer and TA thermometer yielded slopes of 0.93, 0.94 and 0.89, respectively. The slopes were neither different from each other (P=0.70) nor from the value of 1. CONCLUSIONS The TA and esophageal thermometers agree well, and the esophageal-TA and esophageal-rectal temperature agreements are not significantly different.