The role of trauma in the etiology of temporomandibular disorders (TMD) is controversial. The objectives of this study were to compare presenting signs, symptoms, and diagnoses in patients who had motor vehicle accident trauma-related TMD to patients who had nontrauma-related TMD. Files of 50 trauma and 50 matched nontrauma TMD patients were reviewed. Information concerning presenting pain, temporomandibular joint (TMJ) and related symptoms, examination findings, and diagnoses was recorded. Posttraumatic TMD patients reported higher facial (P = .006) and headache (P = .0001) pain ratings, neck symptom frequency (P .01), ear-related symptoms (P = .02), sleep disturbance (P .001), and occupational and avocational disability frequencies (P .0001). They had greater masticato ry muscle (P .001), neck muscle (P .001), and TMJ tenderness (P = .01) scores and myofascial pain (P = .006) and arthralgia/capsulitis (P = .008) diagnoses. The nontrauma group had more subjective (P = .01) and objective (P = .05) TMJ crepitus and higher self-reprots of parafunctional jaw habits (P = .05). Trauma may be an important etiologic factor for some TMD patients.