The prevalence of allergic diseases has increased tremendously over the last decades. Clinically they comprise a spectrum of many different conditions caused by specific immunological hypersensitivity in response to a mostly apathogenic substance. Environmental factors such as lack of immune-stimulating contacts (infection, vaccination) and exposure to allergy-enhancing anthropogenic pollutants from tobacco smoke or traffic exhaust particles are suspected to be involved in the increase of allergies. Recently it has been shown that pollens are not only allergen carriers but also secrete highly active proinflammatory lipid mediators, pollen-associated lipid mediators (PALMs), which have proinflammatory and immuno-modulatory capacity that facilitates allergic sensitization of the skin and mucous membranes. The skin is one of the most important organs where allergic reactions manifest. Many different morphological and physiopathological entities can be observed in the skin that represent all kinds of pathogenetic immune reactions from immediate-type allergy, urticaria, angioedema, anaphylaxis, cytotoxic and immune complex reactions such as thrombocytopenic purpura or allergic leukocytoclastic vasculitis, exanthematous drug eruptions, granulomatous skin reactions to tattoos or fillers as well as a wide spectrum of dermatitis and eczema with allergic contact dermatitis being one of the most common occupational diseases in many countries. Recent progress in pathophysiology has revealed a role of epidermal barrier function as well as immunodeviation in atopic eczema giving rise to new diagnostic and therapeutic strategies. The interdisciplinary character of allergy implies a close cooperation between different disciplines where dermatology plays a major role in the management of allergic diseases, covering diagnostic, therapeutic and preventive aspects.