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Not AvailableRhizoctonia solani is a most destructive soil borne plant pathogenic fungus causing sheath blight of rice. Cultural and morphological variability was studied in eighteen isolates of R. solani collected from different rice growing areas including Haryana, Punjab, UP and Maharashtra etc. Based on the radial colony growth rate, all the isolates were categorised into three groups as slow, medium and fast growing. Majority of isolates showed medium colony growth rate. Hyphal width in all the isolates ranged between 6 to 10.5 μm. Most of the isolates produced raised or fluffy and pale yellow to very pale brown, mycelium with varied patterns of sclerotial formation. Isolates produced brown to dark brown sclerotia which were either present in the form of concentric ring at the centre or periphery or scattered throughout the colony. Studies on morphological characterization of R. solani isolates showed that isolates were highly variable both in mycelial and sclerotial parameters, with no consistent characters related geographic origin. All isolates were found variable in their anastomosis behaviour. Variable hyphal reactions were observed and three groups were speculated based on reaction type between the isolates. Out of 171 possible pairing, 8 pairs showed incompatible reaction, 87 pairs showed wall to wall contact with incompatible reaction, while perfect fusion was occurred in 76 pairs. All isolates showed self compatibility. The results of anastomosis behaviour revealed that all isolates showed compatible reaction were closely related with each other and may be belonged to same AGs subgroup.Not Availabl