This prospective audit was set up to investigate whether migraine sufferers have evidence of IgG-based food intolerances and whether their condition can be improved by the withdrawal from the diet of specific foods identified by intolerance testing. Migraine patients were recruited from primary care practices and a blood sample was taken. Enzyme-linked immunosorbent assays (ELISA) were conducted on the blood samples to detect food-specific IgG in the serum. Patients identified with food intolerances were encouraged to alter their diets to eliminate appropriate foods and were followed up for a 2-month period. Endpoints included identification of the specific foods that the patients were intolerant to, assessing the proportion of patients who altered their diet and the benefit obtained by these patients at 1 and 2 months. Patients reported the level of benefit on a 6-point scale, where 0 = no benefit and 5 = high benefit. Sixty one patients took part in the audit and 39 completed 2 months of investigation. The mean number of foods identified in the IgG test was 5.3 for all participants and 4.7 for those successfully altering their diet. About 90% of patients changed their diet to a greater or lesser extent following the identification of possible food intolerances. A marked proportion of the migraine patients benefited from the dietary intervention, approximately 30% and 40% reporting considerable benefit at 1 and 2 months, respectively. Also, over 60% of patients who reintroduced the suspect foods back into their diets reported the return of their migraine symptoms. This investigation demonstrated that food intolerances mediated via IgG may be associated with migraine and that changing the diet to eradicate specific foods may be a potentially effective treatment for migraine. Further clinical studies are warranted in this area.