Ionoluminescence (IL) of nano crystalline Mg2SiO4:Dy3+ pellet samples bombarded with 100 MeV Si+8 ions with fluences in the range (1.124e22.480) x 10(12) ions cm(-2) have been studied. Two prominent IL bands with peaks at similar to 480 nm and similar to 580 nm and a weak band with peak at similar to 670 nm are recorded. The characteristic peaks are attributed to luminescence center activated by Dy3+ ions due to the transitions F-4(9/2)-> H-6(15/2), H-6(13/2) and H-6(11/2). It is found that IL intensity initially decreases rapidly and then continuous to decrease slowly with further increase in ion fluence. The reduction in the Ionoluminescence intensity with increase of ion fluence might be attributed to degradation of Si-O (2v(3)) bonds present on the surface of the sample and/or due to lattice disorder produced by dense electronic excitation under heavy ion irradiation. (C) 2011 Elsevier B.V. All rights reserved.