Isolates ofBipolaris sorokinianawith hyaline conidia were obtained from subcrown internodes of single plants of fourTriticumspecies grown on land which, 15 years previously, had been planted with seed inoculated with two hyaline-spored strains. All isolates were pathogenic and produced a "toxin" in culture. Three distinct colony types were distinguished and representatives of both mating types, "A" and "a," appeared to be present. The new isolates were compared with isolate K3 which was one of the isolates used in 1956. Isolate K3 was equally pathogenic but produced no "toxin" in culture. On autoclaved straw, conidia of the new isolates were somewhat shorter than those of K3 but were otherwise similar. On minimal medium all the new isolates produced abundant small, subspherical conidia with one to two pseudosepta. Germ tubes were produced from one or both terminal cells.