Natural human hair was modified by the graft polymerization of propylene sulfide in an aqueous medium. The amount of the polymer grafted onto the reduced hair was 0.15-0.19 g on 1.0 g of hair. The grafted polymer was isolated by the hydrolysis of the hair in the polymer-grafted hair under basic conditions and was confirmed to be poly(propylene sulfide) by H-1 NMR, C-13 NMR, and Fourier transform infrared spectra. The number-average molecular weights of the isolated polymers from the grafted products were 10,000-12,000. (c) 2006 Wiley Periodicals, Inc.