Abstract. The study examines the relationship between a categorical and a dimensional personality assessment instrument in patients with Chronic Fatigue Syndrome (CFS). A total of 162 CFS patients were included in the study (91.4% women; mean age 47.5 years). All subjects completed the Spanish versions of the Personality Diagnostic Questionnaire-4+ (PDQ-4+) and the Temperament and Character Inventory-Revised (TCI-R). Results: 78 (48.1%) of the patients presented a Personality Disorder (PD), the most frequent being Cluster C, specifically Obsessive-compulsive disorder, followed by Avoidant disorder. PDs showed a specific pattern of correlation with temperament scales. All PD clusters correlated positively with Harm Avoidance and Self-Transcendence, and negatively with Reward Dependence, Self-Directedness, and Cooperativeness. In a logistic regression analysis, Self-Directedness and Cooperativeness predicted PD presence. The findings are consistent with previous studies in non-CFS samples and suggest that the combination of the Temperament and Character dimensions (low Self-Directedness and Cooperativeness and high Harm Avoidance and Self-Transcendence) correlates with PD severity, and that Self-Directedness and Cooperativeness are associated with PD presence in CFS patients. The integration of these two perspectives expands the current comprehension of personality pathology in CFS patients.