, Phone: þ52 55 5622 5106, Fax: þ52 55 5616 1535A brief topical review of the optical activity of fullerenes, carbon nanotubes, and metallic clusters, is given. Using a recently developed first-principles formalism, the particular case of the optical activity of the chiral C 84 fullerene with D 2 symmetry is studied in detail. In particular, the optical activity of the four possible isomers with this symmetry is studied by calculating the electronic circular dichroism (CD) and compared with experimental data. Although a similar line shape is found for the lowest-energy isomer, the width and intensity of the main experimental peaks are not well reproduced. On the other hand, it is found that the average CD of the mixture of the three lower-energy isomers is in better agreement with experiments. It is expected that this review would be useful as an introduction to optical activity at the nanometer scale, and motivate further experimental studies and the interpretation of natural optical activity in nanoparticles.Calculated CD of a mixture of different isomers of the fullerene C 84 with D 2 symmetry by using DFT and its comparison with experiment.