Allergy is the most common form of immunologic disease. It is defined as an immunologically mediated reaction to a foreign antigen (allergen), causing tissue inflammation and organ dysfunction. The disease can be local or systemic. Because the allergen is foreign (ie. Environmental), the skin and respiratory tract are the organs most frequently involved in allergic disease. Allergic reactions may also localize to vasculature, gastrointestinal tract, or other visceral organs. Anaphylaxis and serum sickness are systemic forms of allergy. Allergic diseases can be classified according to (1) the immunologic mechanism involved in pathogenesis, (2) the organ system affected, and (3) the nature and source of the allergen. An immunologic classification is preferred, because it serves as a rational basis for diagnosis and treatment. Avoidance is the most effective treatment for any allergic condition, and it should always be considered in addition to pharmacologic and immunologic treatment. Avoidance of allergen exposure cures the specific problem, but it may or may not reduce the underlying immunologic sensitivity to that allergen. Some of the allergens like – Pollens – Animal Danders – House Dust and Dust Mites – Mold Spores – Insect Stings – Drugs – Foods – Contactants etc. The scope of homeopathic treatment is very good in curing the allergic diseases as it treats constitutionally and improves the immuno-deficiency.