Temperature manipulations of harvested mature green tomatoes (Lycopersicon esculentum cv. Daniella) were found to decrease chilling injury (CI) development if applied before 2°C storage. The tomatoes developed CI after transfer to 20°C if held for longer than 1 week at 2°C. Gradual cooling to the storage temperature of 2°C prevented injury from developing. Holding the tomatoes for various times at 38°C before storage of up to 4 weeks at 2°C also prevented CI, while this protection disappeared if the tomatoes were transferred from 38 to 20°C for 4 days before 2°C storage. Holding tomatoes at 20°C before storage did not affect CI development. Temperatures higher than 38°C were not generally as effective as 38°C, and 24 h at 42 or 46°C caused heat damage. The ability of mature green tomatoes to ripen after 3 weeks at 2°C increased as the growing season advanced, but there was no similar change in susceptibility to CI. The effect of chilling temperatures on ripening and on the development of CI does not appear to be connected, but a prestorage heat treatment negated the effect of chilling on both processes.