Abstract: Our previous work demonstrated that female TMD patients exhibit enhanced nociceptive processing compared to age matched, pain-free controls1,2. This enhancement, measured as increased temporal summation of pain, was found on the hand – a body site distant from the clinical pain region. This finding suggested that these patients had a global increase in central nociceptive processing. Our model incorporating these observations was that this central nociceptive hyperexcitability was one component contributing to the pain of TMD, and could explain why minor and even undetectable pathology of the TMJ region could result in a distressing chronic pain. These studies only evaluated women, since a large majority of TMD patients are women. Now, we report results from similar testing of male TMD patients. Our temporal summation of mechanical pain protocol was used as described previously1. Sharp probes are repeatedly pressed against the skin of the finger, while the subject reports the perceived pain intensity for the 1st, 5th, and 10th stimulus of the series. While the stimulus force is the same each time, rapid repetition of the stimuli produces a gradually increasing perception of pain, which is attributable to central nociceptive processing summation. Based on data collected to date (n=11), we have observed that male TMD patients do not show temporal summation of pain, which makes them very different from the female TMD patients, who show exaggerated temporal summation of pain. Furthermore, this apparent absence of any temporal summation distinguishes the male TMD patients from healthy male subjects, who demonstrate some temporal summation. The central nociceptive processing upregulation thought to be contributing to TMD pain for women is not present in men. These results suggest a distinct sex difference in the role of altered nociceptive processing for TMD pain. (1. Sarlani, Pain, 2004; 2. Sarlani, Cells Tissues Organs, 2005)