The effect of swift-heavy-ion irradiation on a very stable and well-studied Al62Cu25.5Fe12.5 icosahedral quasicrystalline system is discussed here. The experiments are performed in the pure electronic excitation regime, where various ranges of energy (1.2 to ∼2.5 keV/Å) are systematically deposited in to the system, causing electronic excitations in them. The choice of ions was generally dependent on calculations based on Monte-Carlo simulations and some existing literature studies on metals/metallic alloys. Samples were irradiated at fluences of 1011 to a few 1013 ions/cm2, and a homogeneous irradiation was ensured. The effect of these electronic excitations on the electronic structure of the quasicrystals is analyzed by doing in situ resistivity vs. fluence and ex situ resistivity vs. temperature measurements, made on the irradiated pieces. © 2004 Published by Elsevier B.V.