Anastomosis groups (AG) of R. solani may coinhabit soil and differ in pathogenicity and epidemiology characteristics. Therfore, methods for rapid identification and separation of AG-types would be desirable. Separation of R. solani AG-3 from other Rhizoctonia AG-types was studied on Stewart''s medium and on potato-dextrose agar (PDA). Isolates of R. solani (126), representing AG-1, AG-2, AG3 and AG-4 and 4 isolates of R. solani-like fungi were grown on these media. After incubation on Stewart''s medium, all AG-3 isolates were consistently and uniformly brown; all other isolates were white. On PDA or other common media, the colony appearance of AG-3 isolates was less characteristic. Stewart''s medium might be a useful and rapid tool for differentiating isolates of R. solani AG-3.