A linear instability analysis is performed to arrive at the dispersion relation that governs the instability of an inviscid liquid jet emanated into an inviscid gas. The velocity profile within the jet is varied from parabolic to uniform in order to model the effects of its relaxation on jet instability and intact length. The results indicate that the closer the profile to uniform the more pronounced the instability. In the jet atomization regime, increasing Weber number and/or gas to liquid density ratio promote instability. (C) 2000 Elsevier Science S.A. All rights reserved.