ObjectiveThe purpose of this study was to determine the accuracy and reliability of infrared thermography in the diagnosis of arthralgia in women with temporomandibular disorder. MethodsThirty women aged between 18 and 40 years were recruited for the study. The Research Diagnostic Criteria for Temporomandibular Disorders was used to allocate the volunteers to the control group (n = 15) and arthralgia group (n = 15). Both groups were submitted to infrared thermography of the temporomandibular joint (TMJ), followed by a punctual analysis of the images. The Mann-Whitney U test was used for the comparison of skin surface temperature between groups. The intraclass correlation coefficient was calculated to determine the reliability of the infrared image analysis. The receiver operating characteristic curve was used to determine the accuracy of the diagnosis. ResultsSkin temperature was significantly greater over the left (P = .004) and right (P = .012) TMJ in the arthralgia group. The intraclass correlation coefficient ranged from 0.841 to 0.874. The area under the receiver operating characteristic curve ranged from 0.598 to 0.675. ConclusionExcellent intrarater and interrater reliability was found in the analysis of the infrared images of the TMJ. However, infrared thermography demonstrated a low accuracy in the diagnosis of arthralgia in women with temporomandibular disorder.