Abstract: Fungi with Rhizoctonia-like mycelia were isolated from root and stem of Gladiolus (Gladiolus hybrida L.) grown in commercial glasshouse in Mahallat, Iran, during the summer and fall of 2003. Isolated fungi were identified as either binucleate or multi nucleate Rhizoctonia sp. On the basis of hyphal characteristics and nuclear number, twenty three isolates of Rhizoctonia sp. were obtained from infected corms and stems. Of the 23 isolate, 9 had binucleate and 14 had multinucleate vegetative hyphal cells. Representative isolates of binucleate Rhizoctonia sp. were characterized for anastomosis, optimum temperature in vitro and virulence on Gladiolus. Isolates of binucleate Rhizoctonia failed to anastomose with tester isolates of Anastomosis Groups (AG)-A throug-S (not including AG-J and AG-M). The optimum temperature range for growth rate of binucleate Rhizoctonia sp. was 24-28°C. Growth rate of binucleate Rhizoctonia sp. was more rapid than R. solani. Five isolates from each group caused severe corm rot and mortality of plant during rooting. Isolates of binucleate Rhizoctonia caused corm and stem rot and mortality only on 35-day-old plants. This is the first detailed report of corm and stem rot disease of Gladiolus caused by binucleate Rhizoctonia. Further field studies are needed on the ecology and pathogenicity of Rhizoctonia sp. to formulate steps for controlling corm and stem rot of Gladiolus.