IntroductionHangover headache is a well-recognised and frequently occurring headache. To the best of our knowledge, largescale population studies, with details regarding hangover headache and based on face-to-face interview methodology, have so far not been published in headache literature. Hangover, rather than hangover headache, has been described in detail [1,2].The IHS [3] has described two types of alcohol response: (1) Code no. 8.1.4: ("Alcohol-induced headache") and (2) Code no. 8.3.1: "Alcohol withdrawal headache (hangover)". The first one sets in early. These are the response patterns and criteria that will be adhered to in this context, because they were the available ones at the time of the Vågå study.Recently, the ICHD II has been published [4]. The two variants of alcohol-induced headache have been joined under a common heading: "Alcohol-induced headache" (8.1.4): J Headache Pain (2004) 5:181-187 DOI 10.1007 Hangover headache. Prevalence: Vågå study of headache epidemiology However, due to uncertainty whether hangover headache could be incorporated, this part of the study was started at no. 500. Of the remaining 1338 dalesmen, 1122, i.e., 83.9%, were questioned about hangover headache. The parochial "drinking culture" could probably best be characterised as binge drinking and not as a constant, daily consumption. Inclusion criteria were: intoxication by alcohol; headache; and the headache manifesting itself more than three hours after the end of drinking. In the whole series, 714 dalesmen had experienced hangover headache ("delayed alcohol-induced headache") during their lifetime (64%). This may be the best way to express hangover headache prevalence. Among those who had been "exposed to proper amounts of alcohol", the prevalence was considerably higher: 88%. With the existing drinking pattern, hangover headache clearly dominated in males (M/F ratio: 1.50 vs. 0.72 in those without hangover headache (p<0.0005)). Consistency tests showed high Kappa values.