The ripening of avocado fruit and the development of chilling injury in relation to short heat-treatments has been studied in the cv. Hass . The minimal conditions needed to induce maximal production of heat shock proteins (HSP) in samples of mesocarp tissue were an exposure to 38°C for 4 h. Short heat-treatments applied during the ripening process reduced the maximum rate of ethylene production during the climacteric period, but this was not correlated with lower levels of 1-aminocyclopropane-1-carboxylic acid (ACC). Heat-treatment also hastened the occurrence of the climacteric in fruit treated in the early pre-climacteric period. A similar regime applied to fruit immediately prior to this event delayed the onset of the climacteric. The use of short heat-treatments to overcome the effects of chilling injury was investigated by subjecting the fruit to 38°C for 0, 6, 12, 24, 36 or 48 h prior to transferring them to 0°C for 7, 14 or 21 days. Heating for 6-12 h provided a significant degree of protection from chilling injury and therefore may have potential for extending the period of cold storage.