Communication: Are nanotubes ideally suited to a straightforward reinforcing role? Results reported here indicate that that may not be the: case, but they could find application as a polymer modifier, A successful route is described for the fabrication of large composite films containing carbon nanotubes based on the formation of a stable colloidal intermediate, a route that should bt broadly applicable to a range of nanotube materials and polymers. The resulting thermo-mechanical and electrical properties are discussed. While the stiffness of the composites at room temperature is rather low they show promise at high temperatures.