Photodynamic therapy (PDT) is increasingly being recognized as an attractive, alternative treatment modality for superficial cancer. Treatment consists of two relatively simple procedures: the administration of a photosensitive drug and illumination of the tumor to activate the drug. Efficacy is high for small superficial tumors and, except for temporary skin photosensitization, there are no long-term side effects if appropriate protocols are followed. Healing occurs with little or no scarring and the procedure can be repeated without cumulative toxicity. Considering the efficacy and lack of long-term toxicity of PDT, and the fact that the first treatment of cancer with PDT was done more than 100 years ago, one might expect that this treatment had already become an established therapy. However, PDT is currently offered in only a few selected centers, although it is slowly gaining acceptance as an alternative to conventional cancer therapies. Here, we show the developmental steps PDT underwent and summarize the current clinical applications. The data show that, when properly used, PDT is an effective alternative treatment option in oncology.