We assessed the psychological profile of a large sample of patients with chronic daily headache (CDH) seen in tertiary care. We used a case-control design to study 791 patients who fell into the following categories: ARH group, chronic migraine with analgesic overuse (analgesic rebound headache, ARH), n=399; CM group, chronic migraine (CM) without analgesic overuse, n=158; and new daily persistent headache (NDPH) group, n=69. These groups were compared to two control groups: 1, migraine, n=100; 2, chronic posttraumatic headache (CPTH), n=65. We assessed personality and psychopathology with the Minnesota multiphasic personality inventory (MMPI)-2. The number of patients with Tscores > or =65 and < or =40 were analyzed by the two-sided Fischer's exact test. The ARH and CM groups had a higher number of subjects with T-scores > or =65, when compared to the migraine group, on the following scales: 1 (hypochondrias), 2 (depression), 8 (schizophrenia) and 0 (social introversion). No differences were observed between the NDPH and migraine groups. Considering CPTH as the control group, the pattern we found was quite the opposite of that described above: NDPH group presented a higher number of subjects with T-scores > or =65 on the following scales: 1, 2, 7 (psychasthenia) and 8. ARH and CM groups had significantly higher T-scores for scale 7 alone. NDPH showed T-scores < or =40 in scale 9 when compared to both control groups. We conclude that: (1) psychopathological factors are common in CDH patients, and appear to be a consequence of the chronification process; (2) low scores on scale 9 (hypomania) may relate to the development of NDPH; (3) psychopathological profiles differ among the subgroups of CDH and the MMPI-2 is reliable in identifying such patterns; and (4) psychological assessment is an essential step in the evaluation and treatment of patients with CDH.