Marine fungi are an understudied group of eukaryotic microorganisms characterized by unresolved genealogies and unstable classification. Whereas DNA barcoding via the nuclear ribosomal internal transcribed spacer (ITS) provides a strong and rapid tool for fungal species delineation, accurate classification of fungi is usually arduous given the massive number of partial or unknown barcodes and misidentified isolates deposited publicly databases. this example is perpetuated by a paucity of cultivable fungal strains available for phylogenetic research linked to those data sets. We analyze ITS barcodes produced from a subsample (290) of 1781 cultured isolates of marine-derived fungi within the Bioresources Library located at the Australian Institute of Marine Science (AIMS). Our analysis revealed high levels of under-explored fungal diversity. the bulk of isolates were ascomycetes including representatives of the subclasses Eurotiomycetidae, Hypocreomycetidae, Sordariomycetidae, Pleosporomycetidae, Dothideomycetidae, Xylariomycetidae and Saccharomycetidae. The phylum Basidiomycota was represented by isolates affiliated with the genera Tritirachium and Tilletiopsis. BLAST searches revealed 26 unknown OTUs and 50 isolates like previously uncultured, unidentified fungal clones. This study makes a big addition to the supply of barcoded, culturable marine-derived fungi for detailed future genomic and physiological studies.