A suspension of carbon nanotubes in natural latex was obtained by liquid mixing and then was used to prepare powder natural rubber composites modified with carbon nanotubes by means of spray drying process. The composite powders were round-like and fine, with an average diameter of less than about 5 mu m. The dispersion of carbon nanotubes in the rubber matrix was improved remarkably compared with that obtained by the mechanical mixing method. By means of vulcanization tests, it was found that the addition of vulcanizing agent necessary for the powder rubber containing carbon nanotubes should be evidently greater than that in rubber prepared by mechanical mixing, there evidently existed vulcanization reversions for the natural rubber prepared by mechanical mixing, which disappeared in the powder rubber containing carbon nanotubes prepared by the spray drying process. The mechanical properties of the powder natural rubber containing carbon nanotubes were much improved because of the modification effect of carbon nanotubes in rubber. (c) 2006 Wiley Periodicals, Inc.