Following the discovery of C60 in 1985, photoinduced reactions by fullerenes have been continuously studied since the early 1990s. Important properties of fullerenes as photosensitizers include a relatively long excitation wavelength and efficient generation of reactive oxygen species. Coupled with the lack of reported toxicity of C60 in mammalians in the absence of light, these properties render fullerenes suitable as photosensitizers for photodynamic therapy. To be able to use C60 in biological systems, several approaches were developed to prepare water-soluble fullerene complexes or derivatives thereof. In this talk, 1,3-dipolar cycloaddition reactions of C60, C70, and M3N@C80 for the preparation of water-soluble fullerene derivatives, the use of these compounds for reactive oxygen species generation, and applications of these systems will be discussed.