Nowadays, the concept of clusters is being indiscriminately accepted as an important path to the competitiveness of industries and spatial units. The aim of the paper is to present the concept of the (regional industrial) clusters pointing to its historic predecessors. Above all, reasons that cause its ambiguity and the confronting attitudes of the scientific and political authorities are discussed. Based on the literature study, the problems connected with an especially free and flexible definition and delimitation of clusters are emphasized, as they may offer pragmatic and simple solutions but also cause the numerous theoretical/methodological problems. The paper concentrates on problems associated with identification of the clusters and choice of appropriate methodical approaches for its industrial and spatial delimitation. Some risks connected with the general glorification of the role of clusters in industrial and regional development without taking into account the local and regional specific features are also pointed to.