By Monte Carlo simulations, we investigate the current voltage characteristic and the associated current noise in GaN double-drift impact avalanche diodes. For values of the current multiplication factor greater than ten we find a giant suppression of avalanche noise down to three order of magnitude with respect to the standard excess noise factor. The negative feedback between fluctuations in space charge and in number of generated electron-hole pairs is proven to be the responsible of such a giant suppression. (C) 2004 Elsevier Ltd. All rights reserved.