Nineteen percent of about 490 patients with classical or common migraine reported that headaches can be precipitated by chocolate, 18% by cheese and 11% by citrus fruit, and a highly significant majority of these patients were sensitive to all three foods. Twenty-nine percent of the patients reported sensitivity to alcohol; again this was significantly associated with sensitivity to the three food stuffs, though a substantial number of patients were sensitive to alcohol but not foods. Thirty-one percent of 331 female patients believed that oral contraceptives precipitated headaches, but this could not be related to any dietary response. Patients with affected relatives were significantly more likely to report sensitivity to alcohol and chocolate; sensitivity to cheese and citrus fruit was less strongly related, and there was no relationship at all for oral contraceptives. These correlations suggest that food induced headaches are mediated by chemical constituents common to these foods.