Chitosan (CS)/silk fibroin (SF) blend films containing nanoparticles of methoxy poly(ethylene glycol)-b-poly(d,l-lactide) (MPEG-b-PDLL) were prepared by film casting of nanoparticle suspension-CS/SF blend solution. The nanocomposite blend films with CS/SF blend ratios of 2/0, 2/1, 2/2, 1/2 and 0/2 (w/w) were investigated. FTIR results showed the intermolecular bonds existed between nanoparticles and CS/SF film matrices. The nanoparticles with spherical shape observed from SEM micrographs were approximately less than 1 μm in size and dispersed throughout the film matrices. Nanopores on both film surfaces and cross-sections of the nanocomposite blend films were formed due to self-condensation and phase separation of the nanoparticles. The nanocomposite blend films contained nanoparticles exhibited an increase of film strength and decrease of film flexibility and water wettability. © 2009 Elsevier Ltd. All rights reserved.