The objective of this research was to investigate the effect of chitosan on the interaction of water with bread ingredients and assess the effect of the molecular weight of chitosan molecules on the interaction with protein and starch in bread and on the rate of staling. The changes of freezable bound water and total water contents in bread crumb were assessed by differential scanning calorimetry (DSC) from water melting and evaporation endotherms. It was found that freezable water content and total water conten in bread crumb decreases during staling more rapidly in the presence of chitosan. Two stages of bread crumb staling were indicated. Chitosan increases rate of bread staling during both stages. Chitosan oligosaccharides and low molecular weight chitosan increase bread crumb staling rate to a much less extent than do middle molecular weight chitosan. It was suggested that during bread staling chitosan increases water migration from crumb, prevents amylose-lipid complexation, and increases dehydration rate both for starch and gluten.