Five hundred seventy-seven consecutive patients attending the Princess Margaret Migraine Clinic from 1989 to 1991 have been questioned about dietary precipitants of their headaches. Four hundred twenty-nine patients had migraine, of which 16.5% reported that headaches could be precipitated by cheese or chocolate, and nearly always by both. Of the migraine patients, 18.4% reported sensitivity to all alcoholic drinks, while another 11.8% were sensitive to red wine but not to white wine; 28% of the migrainous patients reported that beer would precipitate headaches. There was a definite statistical association between sensitivity to cheese/chocolate and to red wine (P<0.001) and also to beer (P<0.001), but none between diet sensitivity and sensitivity to alcoholic drinks in general. None of 40 patients with tension headache (diagnosed by International Headache Society criteria) reported sensitivity to foods, and only one was sensitive to alcoholic drinks. The prevalence of sensitivity among 46 patients with some migrainous features was intermediate between the migraine and tension headache categories. It is concluded that cheese/chocolate and red wine sensitivity, in particular, have closely related mechanisms, in some way related more to migraine than to more chronic tension-type headache, while quite separate mechanisms play a major role in sensitivity to alcoholic drinks in general.