Accurate temperature measurement in patients with cancer is critical. Many patients are neutropenic; therefore, fever represents an oncologic emergency, and, in many cases, it can be the only indication of a life-threatening infection. Although oral thermometers most closely represent true core temperature, patients may have barriers to oral thermometry. The purpose of this study was to assess the accuracy of two alternative, noninvasive thermometers (tympanic and temporal artery) by comparing them to an oral thermometer. A method-comparison study design was used. Each participant received three temperature measurements. The dependent variable was the difference in temperature between the test thermometers and the oral thermometer. The results suggest that neither of the test thermometers accurately represented core temperature, particularly in febrile patients. Both the tympanic and temporal artery thermometers became less accurate as oral temperature increased.