The use of photosensitizers in the treatment of skin diseases is not new to the field of dermatology. This concept was first popularized by Goeckerman in 1925 with the use of topically applied crude coal tar and ultraviolet (UV) light to treat psoriasis.1 In more recent years, the use of 8-methoxypsoralen as a photosensitizer in combination with high-intensity UV-A has become a standard form of "photochemotherapy" for psoriasis. Photodynamic therapy (PDT), a term synonymous with photochemotherapy, refers to the combination of a photosensitizer and nonionizing radiation to provide a beneficial therapeutic effect. Use of PDT provides a unique approach for the selective therapy of diseases localized to the skin. By confining the photoactivation of the drug to the disease site in the skin, generalized systemic toxicity can, in theory, be avoided. The addition of new chemicals that sensitize diseased cells and tissues to electromagnetic radiation in the near UV