Objective: Our aim was to deepen the understanding of the psychosomatic aspects of temporomandibular joint (TMJ) pain dysfunction syndrome. Patients affected by this syndrome were compared with both healthy subjects and psychiatric patients, using both self-report and physician-scored psychological measures. Methods: Three sex- and age-matched groups were recruited: a TMJ group (n = 32), a healthy group (n = 22) and a psychiatric group (n = 22). The psychiatric group consisted of outpatients diagnosed as having a DSM-IV anxiety or depressive disorder of mild to moderate severity. Psychometric assessment included the Minnesota Multiphasic Personality Inventory (MMPI) and the Hamilton Anxiety Rating Scale (HARS). Results: Psychiatric patients scored higher than both the comparison groups on all but one of the MMPI scales; the majority of the differences were significant or approached significance. TMJ patients scored higher than healthy controls on the Hs (hypochondriasis; p ≤ 0.01), Hy (hysteria; p ≤ 0.01) and D (depression; p ≤ 0.05) scales. Psychiatric patients scored higher than TMJ patients on the HARS psychic anxiety subscale (p ≤ 0.05), while TMJ patients scored higher than psychiatric patients on the somatic anxiety subscale (p ≤ 0.05). Conclusions: Certain personality characteristics were associated with TMJ dysfunction. However, further longitudinal studies should be performed to properly assess causal relationships. Despite signs of neuroticism, anxiety and depression, patients with TMJ dysfunction differed from anxious and depressed patients. While the latter displayed a higher level of psychopathology, each group was characterised by a distinct pattern of anxiety symptoms. In addition, a substantial proportion of TMJ patients had little awareness of their inner states and emotions.