The type species of Phaeoisaria, P. clematidis (Fuckel) Hughes is described from pure culture. The conidiogenous cells occur on both the synnemata and undifferentiated hyphae. The latter condition is compared with that of the fertile cells of some non-synnematous genera of the Hyphomycetes. Chloridium glaucum Ellis & Everh. is placed in Phaeoisaria and a new species, P. curvata, is described. A key to the species of Phaeoisaria is provided.