Lactic acid fermentation was used to extract chitin from prawn shell (Nephrops norvegicus) at two different scales of operation. The fermentation products were characterized and compared with chitin extracted from the same source by a chemical method. Chitosans produced from the obtained chitins were evaluated in terms of their intrinsic viscosity, molecular weight and degree of acetylation (DA). The fermentation removed 690 g kg(-1) and 770 g kg(-1) of inorganic matter, 490 and 440 g kg(-1) of protein and 540 and 770g kg(-1) of lipids from the shells at laboratory and pilot plant scales, respectively. However, the functional properties such as the DA of the chitin, the molecular weight and the DA of the chitosans were similar to those obtained for the chemically-obtained chitin and its chitosan. Despite the incomplete extraction of chitin this biological process could be useful to produce chitin and chitosan in a more environment-friendly approach. (C) 2004 Society of Chemical Industry.