Because of its easy access, tympanic membrane temperature has enjoyed increasing popularity as an index of deep core temperature during exercise as well as during recovery from exercise. These measurements are made with the assumption that changes in tympanic membrane temperature reflect changes in deep body temperature and, therefore, can be used as an index for the treatment of hyperthermia. In the present study, we report measurements of tympanic, esophageal and skin temperature in subjects exercising at constant (n = 6) or incremental (n = 4) work loads, and during recovery from exercise. Fanning of the upper chest was applied during recovery in two of the subjects who repeated the constant load exercise. Tympanic temperature was lower than esophageal during constant and incremental load exercise (p< 0.025 andp< 0.05, respectively). For both constant and incremental load exercise, there was a delay in the increase in tympanic temperature and the magnitude of the change was less than that of esophageal temperature. Furthermore, during recovery from steady state exercise, while tympanic and skin temperatures still increased, esophageal temperature readily decreased. Finally, because fanning influenced both tympanic and skin temperature changes and had little effect on esophageal temperature, we conclude that tympanic membrane temperature is influenced by rapid changes in skin temperature and should not be used to assess the thermal state of athletes during exercise or during recovery from exercise.