Background: The hypothalamus has been discussed as a pivotal structure for both cluster headache (CH) and aggressiveness, but little is known about the extent of self-reported aggressiveness in patients with CH. Patients and methods: Twenty-six patients with chronic, 25 with active episodic and 22 with episodic CH outside the active period were examined interictally with a validated questionnaire quantifying factors of aggression and compared with 24 migraine patients and 31 headache-free volunteers. Results: The ANOVA was significant for the subscale 'self-aggression/depression' (F-4,F- 123 = 5.771, p < 0.001) with significant differences between chronic and episodic CH and healthy volunteers. No significant changes were found for other subscales and the sum scale (F-4,F- 123 < 1.421, p > 0.230). Especially in the clinically most affected group of patients (chronic CH and active episodic CH), high levels of "self-aggression/depression" correlate with higher prevalence of depressive symptoms and higher impairment measured on an emotional and functional level. Discussion: Self-aggressive and depressive cognitions with highest scores in chronic CH seem to be reactive as they correlate with depressive symptoms and impairment. They should be considered as an important therapeutic target since they impair the patient's life significantly.