Isolates of Rhizoctonia solani were obtained mainly from soil collected from different areas representing major agro ecological zones of Bangladesh. Isolates were also collected from potato tuber and stem, mungbean, seedlings of cauliflower and cabbage, amaranth and grass like Imperata cylindrical L (ulu.). To isolate the fungus from soil, sterilized dry buckwheat stems were used as baits. The stems were cut into small pieces and put it into the soil at 10-15 cm depth for 3-5 days. Then the pieces of bait were recovered from the soil and washed in a jet stream of tap water for one hour. After washing, bait materials were kept into 200ppm streptomycin sulphate solution for 10 minutes and blotted with sterilized blotting paper. The baits were then plated (two pieces per plate) on Petri dishes containing 1.5% water agar (WA) amended with 200 ppm streptomycin sulphate and 100 ppm metalaxyl. In case of plant samples infected tissues were cut into small pieces (1-2 cm) along with healthy tissues. The pieces were washed in tap water and surface sterilized by dipping in 70% ethanol for 30 sec. The surface sterilized specimens were rinsed three times with sterilized water. The excess water on the surface of the cut pieces were removed by blotting with sterile blotting paper and plated on 1.5% water agar medium containing 200 ppm streptomycin sulphate and 100 ppm metalaxyl. For both the cases, the plates were incubated at 25 ± 10 C. After appearance of the characteristic growth of the fungus, hyphae were transferred aseptically to Petri dishes containing solidified potato dextrose agar (PDA) amended with 200 ppm streptomycin sulphate. Contamination free plates were selected and young mycelium was transferred to PDA slants in test tubes to obtain pure culture of individual isolate. The test tube having sufficient growth was preserved in refrigerator at 100C. All the collected isolates were studied for cultural and morphological characters by growing them separately on PDA plates. Data were collected on mycelial growth rate after 24 hours of incubation, structure, zonation no., colour of the colony, number of sclerotia/cm2, colour of sclerotia, shape and size of sclerotia, days to sclerotial initiation and the formation patterns of sclerotia. Variations among the isolates based on cultural and morphological characters were analyzed following cluster analysis (CLSA). Among the 50 isolates of R. solani, five homogeneous groups were identified. Five isolates, namely DIN-8, GAZ-9, JES-16, GAZ-18, and SYL-30 taking one isolate from each cluster group were selected to study the host range and pathogenicity. Thirty five crop species, namely wheat, rice, maize, prosomillet, foxtail millet, barley, sorgham, groundnut, soybean, sunflower, mustard, sesame, niger, safflower, chickpea. blackgram, lentil, grasspea, mungbean, cabbage, cauliflower, radish, stringbean, spinach, Indian spinach, Lady’s finger, country bean, carrot, cucumber, white gourd, ribgourd, tomato, brinjal, potato and kangkon were tested against the isolates under field and laboratory conditions.