Chestnut (Castanea sativa Mill.) is an economically important fruit and timber crop worldwide, including Italy. The quality of chestnut fruits can be affected in pre- and post-harvest by insects and molds. Since 2005, chestnut growers in Italy have been suffering increasing yield losses, due to the rotting of the ripe nuts both before and after picking. In 2014 chestnut losses reached more than 50% in some regions of Southern and Northern Italy. The factors that are influencing the growing incidence of the diseases can be related to climate change. Abundant rain during winter and springtime are favoring the development of chestnut pathogenic fungi. Moreover, in Italy chestnuts are normally subjected to “curatura”a practice used with the purpose of killing the larvae of pests (mainly Curculio elephas and Cydia spp.). This method consists in submerging the chestnuts in hot water (50 °C) for 45 min and cooling them in water at 15-18 °C for the same time. This procedure, although can be effective against the pests, may favor the development of molds during postharvest. After 2 years of investigation on chestnut postharvest problems in the Campania region (South of Italy), we found that from both, healthy and rotting chestnut fruits, the most commonly isolated fungi were Gnomoniopsis castanea, followed by Fusarium spp., Penicillium spp. and Aspergillus spp. It is known that these last two genera include several species of strong mycotoxin producers. The aim of our study was to find possible solutions to prevent chestnut yield losses during postharvest. Therefore, we investigated the possibility to add to the water used for “curatura” biological products derived from the biocontrol fungus Trichoderma harzianum. We found some compounds and mixtures that incorporated into the “curatura” can significantly increase the shelf life of chestnuts during postharvest.