Studies were carried out from September, 1986 to June, 1989 to collect a large amount of diseased leaves, in order to find out the causal organisms of Ginkgo leaf blight. Among collections of diseased leaves from all parts of Jiangsu, 3 fungi were identified by means of tissue isolation and inoculation tests as the causal organisms of the disease. They were Alternaria sp., Colletotrichum sp. and Pestalotia sp. On the basis of the differences between their pathogcnicity, the quantity and time of occurrence, we preliminarily considered that, Alternaria sp. was the first important pathogen and then Colletotrichum sp. and Pestalotia sp. respectively.