In this work we describe a novel method for highly efficient functionalization of single wall carbon nanotubes (SWCNTs) by DNA wrapping. Exposure of SWCNTs to gamma-irradiation (50 kGy) has lowered by one order of magnitude the amount of single stranded deoxyribonucleic acid (ssDNA) required for SWCNT modification. The resulting hybrids of gamma-irradiated SWCNTs and ssDNA were characterized by optical absorbance spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy. Atomic force microscopy was used to investigate the morphology of hybrids. While gamma-irradiation in three different media has significantly improved the process of SWCNT dispersion, irradiation in ammonia was the most efficient. The gamma-irradiated SWCNTs functionalized with ssDNA were stabilized by electrostatic forces. This preliminary study suggests that gamma-irradiation can significantly improve the functionalization of SWCNTs with DNA.