Leptosphaeriaceae is a family in the order Pleosporales comprising economically important plant pathogens. Species may also be endophytes or saprobes on various host plants. In recent classifications Alternariaster, Leptosphaeria, Neophaeosphaeria, Paraleptosphaeria, Heterospora, Subplenodomus and Plenodomus were included in the family. The taxonomy of genera and species in Leptosphaeriaceae has been problematic due to the lack of understanding of the importance of morphological characters used to distinguish taxa, as well as the lack of reference strains. In order to establish evolutionary relationships and to provide a backbone tree for Leptosphaeria and allied genera, we sequenced the 18S nrDNA, 28S nrDNA, ITS, RPB2, TEF and ACT gene regions of Leptosphaeriaceae species and analysed this data. Multi-locus phylogenies together with morphology robustly support the monophyletic nature of Leptosphaeriaceae among the other families in Pleosporales, and the inclusion of the genera Alternariaster, Heterospora, Leptosphaeria, Paraleptosphaeria, Sphaerellopsis, Subplenodomus, Plenodomus and three novel genera Alloleptosphaeria, Neoleptosphaeria and Pseudoleptosphaeria. Five new species, Alternariaster centaureae-diffusae, Leptosphaeria cichorium, Paraleptosphaeria rubi, Plenodomus guttulatus and P. salviae are introduced. An account of sexual morph of Alternariaster centaureae-diffusae is provided, and the sexual morph of Leptosphaeria doliolum is re-described and illustrated using modern concepts from fresh collections. A novel family Neophaeosphaeriaceae is established to accommodate the genus Neophaeosphaeria and its species.