We here taxonomically revise the suborder Massarineae (Pleosporales, Dothideomycetes, Ascomycota). Sequences of SSU and LSU nrDNA and the translation elongation factor 1-alpha gene (tef1) are newly obtained from 106 Massarineae taxa that are phylogenetically analysed along with published sequences of 131 taxa in this suborder retrieved from GenBank. We recognise 12 families and five unknown lineages in the Massarineae. Among the nine families previously known, the monophyletic status of the Dictyosporiaceae, Didymosphaeriaceae, Latoruaceae, Macrodiplodiopsidaceae, Massarinaceae, Morosphaeriaceae, and Trematosphaeriaceae was strongly supported with bootstrap support values above 96 %, while the clades of the Bambusicolaceae and the Lentitheciaceae are moderately supported. Two new families, Parabambusicolaceae and Sulcatisporaceae, are proposed. The Parabambusicolaceae is erected to accommodate Aquastroma and Parabambusicola genera nova, as well as two unnamed Monodictys species. The Parabambusicolaceae is characterised by depressed globose to hemispherical ascomata with or without surrounding stromatic tissue, and multi-septate, clavate to fusiform, hyaline ascospores. The Sulcatisporaceae is established for Magnicamarosporium and Sulcatispora genera nova and Neobambusicola. The Sulcatisporaceae is characterised by subglobose ascomata with a short ostiolar neck, trabeculate pseudoparaphyses, clavate asci, broadly fusiform ascospores, and ellipsoid to subglobose conidia with or without striate ornamentation. The genus Periconia and its relatives are segregated from the Massarinaceae and placed in a resurrected family, the Periconiaceae. We have summarised the morphological and ecological features, and clarified the accepted members of each family. Ten new genera, 22 new species, and seven new combinations are described and illustrated. The complete ITS sequences of nrDNA are also provided for all new taxa for use as barcode markers. Key words: Coelomycetes, Freshwater ascomycetes, Helminthosporium, Holomorph, Hyphomycetes, Massarina, Periconia, Spegazzinia. Taxonomic novelties: New families: Parabambusicolaceae Kaz. Tanaka & K. Hiray., Sulcatisporaceae Kaz. Tanaka & K. Hiray; New genera: Aquastroma Kaz. Tanaka & K. Hiray., Clypeoloculus Kaz. Tanaka & K. Hiray., Fuscostagonospora Kaz. Tanaka & K. Hiray., Gregarithecium Kaz. Tanaka & K. Hiray., Magnicamarosporium Kaz. Tanaka & K. Hiray., Neoophiosphaerella Kaz. Tanaka & K. Hiray., Parabambusicola Kaz. Tanaka & K. Hiray., Pseudocoleophoma Kaz. Tanaka & K. Hiray, Pseudoxylomyces Kaz. Tanaka & K. Hiray., Sulcatispora Kaz. Tanaka & K. Hiray; New species: Aquastroma magniostiolata Kaz. Tanaka & K. Hiray., Aquilomyces rebunensis Kaz. Tanaka & K. Hiray., Clypeoloculus akitaensis Kaz. Tanaka & K. Hiray., Clypeoloculus hirosakiensis Kaz. Tanaka & K. Hiray., Clypeoloculus microsporus Kaz. Tanaka & K. Hiray., Clypeoloculus towadaensis Kaz. Tanaka & K. Hiray., Dictyosporium pseudomusae Kaz. Tanaka, G. Sato & K. Hiray, Fuscostagonospora sasae Kaz. Tanaka & K. Hiray., Gregarithecium curvisporum Kaz. Tanaka & K. Hiray., Helminthosporium massarinum Kaz. Tanaka, K. Hiray. & Shirouzu, Keissleriella breviasca Kaz. Tanaka & K. Hiray., Keissleriella quadriseptata Kaz. Tanaka & K. Hiray., Keissleriella yonaguniensis Kaz. Tanaka & K. Hiray, Lentithecium pseudoclioninum Kaz. Tanaka & K. Hiray., Magnicamarosporium iriomotense Kaz. Tanaka & K. Hiray., Periconia homothallica Kaz. Tanaka & K. Hiray, Periconia pseudodigitata Kaz. Tanaka & K. Hiray., Pseudocoleophoma calamagrostidis Kaz. Tanaka & K. Hiray., Pseudocoleophoma polygonicola Kaz. Tanaka & K. Hiray, Stagonospora pseudoperfecta Kaz. Tanaka & K. Hiray., Sulcatispora acerina Kaz. Tanaka & K. Hiray., Sulcatispora berchemiae Kaz. Tanaka & K. Hiray; New combinations: Lentithecium clioninum (Kaz. Tanaka, Sat. Hatak. & Y Harada) Kaz. Tanaka & K. Hiray., Neoophiosphaerella sasicola (Nagas. & Y Otani) Kaz. Tanaka & K. Hiray., Parabambusicola bambusina (Teng) Kaz. Tanaka & K. Hiray., Pseudoxylomyces elegans (Goh, W.H. Ho, K.D. Hyde & K.M. Tsui) Kaz. Tanaka & K. Hiray., Setoseptoria arundinacea (Sowerby) Kaz. Tanaka & K. Hiray., Setoseptoria magniarundinacea (Kaz. Tanaka & Y Harada) Kaz. Tanaka & K. Hiray., Stagonospora bicolor (D. Hawksw., W.J. Kaiser & Ndimande) Kaz. Tanaka & K. Hiray; Epitypifications (basionyms): Phaeosphaeria arundinacea var. brevispora Nagas. & Y. Otani, Phaeosphaeria sasicola Nagas. & Y. Otani.