Photodynamic therapy (PDT) is a medical treatment in which a combination of a photosensitizing drug and visible light causes destruction of selected cells. Over the past two decades, photodynamic therapy has enjoyed a period of laboratory and in the clinic. Although still widely considered to be an experimental technique, its status and value within modern clinical practice continues to grow. The PDT field has, to date, been dominated by a small number of pharmaceutical companies inhabited almost exclusively by clinicians and those involved in fundamental scientific research. True pharmaceutical formulation development has been limited, to some extent, by financial constraints. If PDT is to realize its undoubted potential in clinical practice it is important that awareness of the need for appropriate photosensitizer delivery systems is raised. Accordingly, this article deals with the innovations pertaining to drug delivery systems for photodynamic therapy as disclosed in recent patent literature.