The effects of intense laser and energetic ion irradiation on Raman vibrational modes of Multiwalled Carbon Nanotubes have been investigated. The intensity ratio of D and G modes decreases with increase in laser power density and remains almost constant with decrease of laser power density. The intensity ratio of D mode to G mode for ion irradiated Multiwalled Carbon Nanotubes decreases at low fluence (4 x 10(11) ions/cm(2)) and increases further with increase in ion fluence. The results show that ion irradiation at low fluence and laser irradiation lead to purification/ordering of the nanotubes. (C) 2008 Elsevier B.V. All rights reserved.