In the pharmaceutical area, fine particles with a narrow particle size distribution are required to obtain a high surface area. In addition, particle size is one of the critical factors for the determination of appropriate routes of drug administration. In this work, we have used dense-gas anti-solvent crystallization techniques for the straightforward production of micron-sized powders of the chitosan derivatives D-Glucosamine Hydrochloride and D-Glucosamine Sulphate salts, which have increasing interest at present in medicinal research. The use of these crystallization methods permit to avoid the problematic communition and homogenization down-stream processes steps required after conventional crystallization methods. Semi-continuous ASES and batch GAS procedures, which are the two extremes of dense gas anti-solvent precipitation techniques, were successfully used for the micronization of these salts, and the results obtained with both procedures are compared and analysed. (C) 2005 Elsevier B.V. All rights reserved.