Abstract— Hypocrellins A and B are pigments which are isolated from parasitic fungi Hypocrella bambuase (B. et Br) sacc. and Shiraia bambusicola P. Heen found in the People's Republic of China (P.R.C.) and Sri Lanka respectively. These agents, which belong to the general class of perylene quinonoid pigments, have a long history as traditional medicinal agents especially in the P.R.C. Recently their marked photosensitizing properties have been established and exploratory studies initiated. This effort has led to the realization of the potential of the hypocrellins for the photodynamic therapy of tumors. The review summarizes the chemical and photophysical properties of the hypocrellins and their derivatives as well as studies on photosensitization to date at the molecular, cellular and in vivo levels, and their prospects as PDT agents.