A b s t r a c t .We give two characterizations of the isolated singularities of the local resolvent function of an operator T E L ( X ) at a point z of a complex Banach space X: in terms of a suitable decomposition of x, and in terms of the existence of a sequence in X related with the Laurent series of the local resolvent function. Moreover, we introduce the locally chain-finite operators at a pointx E X and show that T is chain-finite if and only if T is locally chain-finite at every x E X.