Chitosan membranes of three types: i) dried in ammonia atmosphere (CSA); ii) double layer crosslinked with glutaraldehyde (CSG); and iii) prepared from aqueous-ethanolic solution and dried in the presence of ammonia vapor (CSE) were developed by casting chitosan solutions onto a glossy paper used as a support in the process of filtration under high pressures. All the membranes were characterized by infrared spectroscopy, scanning electron microscopy and by permeation experiments. Addition of ethanol to the chitosan solution decreased the time of membrane preparation and of the filtration process. The performance (solute rejection) of these membranes was found to be efficient with organic compounds such as methylene blue, truncated hemoglobin and bovine serum albumin (BSA) with molecular weights of 319.8 Da 17.7 kDa and 66.4 kDa respectively, since it retained practically 100% of the sample.