DNA-wrapped nanotubes of both multiwalled and single-walled carbon nanotubes were obtained by a solid-state mechanochemical reaction. Scanning electron microscopic images show that the nanotubes were cut into shorter lengths and were fully covered with DNA, which was further confirmed by fluorescence microscopy. This resulted in a high aqueous solubility of the products with a stability of > 6 months. The results show that nanotubes were cut also with uniform distribution where > 90% of the multiwalled products were 500 nm to 3 mu m and 80% of the single-walled products were 250 nm to 1 mu m in length, respectively. UV-vis spectra and gel electrophorosis show that the DNA in the product is intact. This facile technique for obtaining supramolecularly masked, water-soluble carbon nanotubes by a solid-state reaction has a great potential for both biological and nonbiological applications of nanotubes.