A dry rot in chestnut fruits, previously not reported in Chile, was shown to be caused by Fusicoccum castaneum Sacc. Genus and species were determined at the Commonwealth Mycological Institute (Nº 271068). The fruit symptoms consisted in internal dry brown necrosis, without external symptoms. F. castaneum was consistently isolated from these fruits. Healthy fruits, inoculated with the fungus, developed identical symptoms and F. castaneum was readiIy re-isolated from the inoculated fru its. Epidemiological information is given.