Summary -Trends in the fracture strain, modulus of deformability and chemical properties as a function of storage time were determined for Cheddar cheese made in the New Zealand Dairy Research Institute' s pilot plant. The apparent fracture strain of Cheddar cheese increased during the first 14---28days and thereafter decreased, asl-Casein levels decreased monotonically and non-protein nitrogen levels increased with storage. Fusion of curd particles probably contributed to the initial increase in fracture strain, and the decrease in strain can be rationalized in terms of increasing proteolysis, The modulus of deformability increased by at least a factor of two over the initial several weeks of storage and then increased slightly or remained constant. However, the moi sture content of Cheddar cheese changed very little (the maximum range being 34.6-33.0% with no monotonie change over time). The increase in the modulus over the first 14 days was not associated with a decrease in moisture content. Differentiai scanning calorimetry indicated there was sorne crystallization of milkfat from 91 to 210 days of storage, and this (together with small moisture los ses) may partly explain the small increase in the modulus of deformability over this period of time.