Variability among 8 isolates of Sclerotinia sclerotium associated with stem rot of chickpea , collected from six governorates of Egypt namely Assiut , Minia , Beni-Suef , Beheira , Gharbia and Kafr El-Sheikh was studied . The isolates varied in their aggressiveness, with Gharbia isolate being the highest 70.0 %, while Assiut isolate was the lowest (5.0 %). Also, the results indicated that environmental conditions and geographic location have some effects on the aggressiveness of isolates, growth of mycelium and size of sderotia. Also the isolates varied in their mycelial growth rate, type of mycelium, weight and size of sclerotia and color of substratum. Variability among isolates on the basis of their mycelia! compatibility was also observed for 28 combinations. More than half (60.71 %) showed compatible reactions. Four types of vegetative compatibility reactions were defined as gap, line-gap, barrage, and compatible reaction types. Aggressive isolates were less compatible with other isolates and their mycelium was fast-growing and bate the mycelium growth of other Isolates and be tried in biocontrol tests.