Orbital phlebography has previously been found to be pathologic in 8 of 13 patients with episodic cluster headache. To compare the frequency and pattern of the pathologlc findings in cluster headache with those In other headache categories, orbital phlebographies were carried out in patients with cluster headache, cervicogenic headache, migraine and tension-type headache (tension headache). The investigations were evaluated Independently by two radiologists, one of whom had no knowledge of the diagnoses. The frequencies of pathologic findings were at maximal 2/12 in the cluster headache group, 2/11 in the cervicogenic headache group, 5/ 12 in the migraine group and 5/15 in the tension-type headache group. The investigators agreed completely in the evaluation of 39/50 phlebograms, with lesser disagreements in 7. In conclusion, the frequency of pathologic findings at orbital phlebography in cluster headache was not higher than in the other diagnostic categories investigated, and the pattern of the pathology was generally the same.