Atopy is an inherited tendency of producing immunoglobulin E on common proteins from the environment like pollen, house mites and food. The presence of atopy represents a risk for the development of allergic diseases like atopic dermatitis, asthma, allergic rhinitis and food allergy, although atopy can also be present only in the form of asymptomatic sensitization. Allergic diseases share common inherited and environmental risk factors, immunologic patterns of allergen-specific Th2 response and efferent phase of immunologic reaction characterized with the production of IgE and activation of granulocytes. The presence of one disease increases the risk for developing other diseases. Allergic diseases demonstrate characteristic sequence of incidence in childhood which is called allergic/atopic march and starts with atopic dermatitis in early infancy. Disrupted integrity of the skin in atopic dermatitis contributes to the development of sensitization and increases the risk for development of other allergic diseases. The discovery of filaggrin gene mutation opens the possibility for causative incidence of allergic diseases and for prevention of development of atopic march. But, the causal link from atopic dermatitis to asthma is still a matter of debate.