Brn1, a reductase gene involved in the melanin biosynthetic pathway, was adopted for species delimitation among members in the "geniculata" group of Curvularia species and proved to be useful for this purpose. Phylogenetic trees of these fungal members were constructed from nucleotide sequences of this region. The so-called geniculata group of Curvularia was separated into several clusters. The conidial morphology of the members in each cluster is closely similar but clearly different among discrete clusters. The phylogenetic groups almost concurred with the morphological grouping. Thus, the synonymous treatment of Curvularia affinis, C. fallax, and C. senegalensis to C. geniculata in a previous study was supported. The isolates with warping hilum conidia were clearly different from C. geniculata and separated into two clusters. C. geniculata ATCC 6671 made an independent duster situated near these clusters. The protuberant hilum species were located separately in the phylogenetic trees. For sound taxonomic treatment of these isolates, we should accumulate more information and retain our species determination for them.