The effect of nonlinear polarization rotation of elliptically polarized laser pulses in solutions of fullerene (C70) in organic solvents and their mixtures has been experimentally studied. The nonlinear refractive index n2 and nonlinear cubic susceptibility Reχ(3) (ω;ω,ω,-ω) of these solutions have been defined. The correlation between the process of C70 cluster formation in solutions and the angle of self-induced polarization rotation of passing laser beam was demonstrated. The physical mechanism of self-induced optical activity in solutions is discussed.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.