Photosensitivity is being recognized increasingly as an important factor in skin disease. Not only do photoallergic reactions occur without specific known etiology, but phototoxic and photoallergic reactions can be induced by many of the drugs which are being introduced into medical practice. Practical means of environmental control for protecting the patient from the ultraviolet or visible radiation to which he is sensitive is becoming increasingly important. Merely telling a patient to stay out of the sun and to avoid fluorescent lamps may produce an unnecessary degree of disability which can be avoided by paying attention to the spectral composition of the light which produces his disease and manipulating the environment appropriately. This paper discusses plastic filter materials which can be used to protect light-sensitive patients. In the past those individuals sensitive only to wavelengths shorter than 3,200 A. could be protected by window glass. However, the protection of individuals sensitive