Isolates of Colletotrichum graminicola from annual blue grass and creeping bent grass were investigated for their morphological characteristics, host specificity, and genetic relatedness. One isolate from maize and one from sorghum (C. sublineolum) were included for comparison. Recently isolated cultures of C. graminicola from annual blue grass were readily distinguished from those isolated from creeping bent grass on the basis of pigmentation. Differences in appressoria size and shape were found only between the turf grass isolates and those from maize and sorghum. Spore length varied significantly between host groups. Differences in host range and virulence were also apparent. In general, isolates from creeping bent grass incited disease on both creeping bent grass and annual blue grass, while those from annual blue grass essentially were limited to host. Random amplified polymorphic DNA (RAPD) marker analysis of C. graminicola isolates from turf grass revealed that a high degree of genetic similarity exists among isolates recovered from the same host, but exceptions were found. Therefore, an absolute distinction between isolates recovered from two turf grass hosts could not be made based on RAPD markers.