Biologic therapy has been used for decades in various diseases in such fields as oncology, endocrinology, gastroenterology and rheumatology. Therapeutic action of biologicals is associated with mimicking the actions of normal human proteins. Several biologic agents function as immune response modifiers, engaging the body’s immune system to combat disease. Recently, a new era of biologic therapy has begun also in dermatology. Monoclonal antibodies, fusion proteins and recombinant human proteins are being applied in miscellaneous skin conditions. Biological therapy appears to be effective particularly in psoriasis and psoriatic arthritis, but researchers and patients also have high hopes of success of biologicals in atopic dermatitis, connective tissue diseases and bullous diseases.