Mushrooms show significant losses in firmness due mainly to the changes in cell walls after harvest. This study was performed to determine the effects of CaCl2 and hot water dips on the changes in firmness, cell wall composition and hydrolase activities of mushrooms during storage. Mushrooms were treated with various concentrations of CaCl2 and hot water at various degrees and stored for 12 days at 10C. The results showed that the firmness of mushrooms decreased significantly and their cell walls have undergone significant changes during 12 days storage period after harvest. Polysaccharide content decreased significantly during storage. This decrease was mainly due to the decrease in the strong alkaline-soluble polysaccharides. Xyloglucanase and beta glucanase activities increased significantly during storage, possibly contributing significantly to the polysaccharide losses. CaCl2 and hot water treatments significantly reduced the changes in cell wall components and cell wall hydrolase activities. The results suggest that CaCl2 and hot water treatments could be used to reduce the changes in firmness and cell walls after harvest and extend the shelf life of mushroom.