One can show the prevalence, the incidence, the course, and especially the results of a disease via epidemiologic studies, but comparison of the results of different investigations is important. This study was planned to determine the cumulative prevalence of allergic diseases in Izmir, the third largest city in Turkey. Many investigators have explored the prevalence of allergic disease and bronchial asthma in their countries. Various methods are used to find the correct prevalence. The safety, easiness, and usefulness of the questionnaire forms are very important.