The purpose of the present study was to assess a group of patients with chronic tension-type headache (CTTH) and control subjects using the personality questionnaire proposed by Cloninger and to determine possible changes in the Temperament and Character Inventory (TCI) patterns of CTTH patients after therapy with serotonergic antidepressants. Forty-five patients with CTTH filled out the TCI and Beck Depression Inventory (BDI) before and after 4-month prophylactic therapy with serotonergic antidepressants. A total of 50 age-, sex- and education level-matched healthy subjects were selected as a control group. During the pretreatment period patients were found to have higher harm avoidance and lower self-directedness scores than healthy comparison subjects. During the post-treatment period, although harm avoidance scores decreased and self-directedness scores increased, harm avoidance scores were still significantly higher and self-directedness scores significantly lower in CTTH patients than in controls. After using BDI score and age as covariates at the post-treatment period, harm avoidance scores were still higher in patients with CTTH while self-directedness scores did not differ between CTTH patients and controls. These findings suggest state and trait dependence of harm avoidance, and strong state dependence of self-directedness scores in CTTH patients. When interpreting data regarding personality measured by the TCI in CTTH patients, the effects of depressive symptomatology should be taken into account.