Allergy reactions are the most common immunological diseases and represent one of the most widespread and fast growing chronic human health problems among people over 15 years of age in developed countries. As populations get older worldwide, allergy manifestations in aged persons will occur more often in the future. To date, there has been much more studies on allergies in children than in adults. As the population ages, clinicians must be prepared to meet all the elderly's health care needs, including these new and emerging health issue. Allergic diseases represent an old/new emerging health issue. Because many common illnesses masquerade as atopic disease, the differential diagnosis of suspected allergic diseases becomes more expanded in an aging population. Research in the field needs to focus on both human and animal model systems to investigate the impact of the aging process on the immunologic pathways underpinning allergy and its different facets.