Diaporthe (Diaporthaceae, Diaporthales) is a common fungal genus inhabiting plant tissues as endophytes, pathogens and saprobes. Some species are reported from tree branches associated with canker diseases. In the present study, Diaporthe samples were collected from Alnus glutinosa, Fraxinus excelsior and Quercus robur in Utrecht, the Netherlands. They were identified to species based on a polyphasic approach including morphology, pure culture characters, and phylogenetic analyses of a combined matrix of partial ITS, cal, his3, tef1 and tub2 gene regions. As a result, four species (viz. Diaporthe pseudoalnea sp. nov. from Alnus glutinosa, Diaporthe silvicola sp. nov. from Fraxinus excelsior, D. foeniculacea and D. rudis from Quercus robur) were revealed from tree branches in the Netherlands. Diaporthe pseudoalnea differs from D. eres (syn. D. alnea) by its longer conidiophores. Diaporthe silvicola is distinguished from D. fraxinicola and D. fraxini-angustifoliae by larger alpha conidia.