We studied a group of 93 patients who had not previously suffered headache and who were consecutively admitted to the Emergency Department of the hospitals of Novara and Borgomanero, Italy because of a cranial trauma definable as minor according to the current International Headache Society (IHS) criteria. Two weeks after admission, all patients underwent a semi-structured interview which revealed that 24 (25.8%) had headache; 21 of these (22.5% of the original 93 patients) also had headache when they underwent a second interview eight weeks after the traumatic event. These 21 patients were diagnosed as having chronic post-traumatic headache associated with minor cranial trauma (5.2.2 of the IHS classification), and the prevalent clinical pattern of headache presentation was examined with the aim of attributing the fourth IHS classification code number. Eighteen of the 21 patients were found to have a tension-type pattern (5.2.2.2), and the remaining three had migraine (5.2.2.1); none had cluster headache (5.2.2.3). These data demonstrate a large prevalence of tension-type headache in patients with class 5.2.2 post-traumatic headache, and confirm the results of previously published studies that were not based on the diagnostic criteria of the current classification.