Cryphonectria parasitica, the causal agent of chestnut blight, was first observed in Spain in Vizcaya in 1947 (Elorrieta, 1949). In the Autonomy of Castilla y León it was detected in 1978 in Bembibre (León) (De-Ana-Magán, 1984) causing damages on chestnut groves. At present, the chestnut blight can be found in many chestnut stands in León and Zamora and in some stands in Salamanca and Ávila where C. parasitica has been recently found. To determine the number of vegetative compatibility groups in Castilla y León and the distribution of these groups across the region, a total of 516 isolates of C. parasitica were studied. Six vegetative compatibility (vc) types were identified among the isolates. Three vc types were compatible with vc types from the European collection (EU1, EU12, EU11), whereas three were new (CL4, CL5 and CL6). The most widespread isolates were EU11 (50,6%) and EU1 (39,9%). The number and diversity of vc types in each population was low.