The title of this thesis is "The relevance of the economic situation of concerns concerning labour law?. It consists of three topics. They have a special relevance in regard to concerns. Concerns as associations of legally independent enterprises, have great importance not only in Austria but also in the international area. Although the different concern enterprises are legally independent, they are not economically independent. This fact leads in the practice to many questions. Because of the fact, that there is no full ?concern law? in Austria, in many cases the jurisdiction has to find the correct answers to these questions. The first topic is about transfers of undertakings, businesses or parts of undertakings or businesses between concern companies. First, some relevant national and European legal provisions, as well as some judgments are discussed. Following, the § 3 Abs 2 AVRAG is discussed. In this connection the question is, if concerns can avoid the ex-lege devolution of the employments according to § 3 Abs 1 AVRAG in connection with the transfers of undertakings, businesses or parts of undertakings or businesses between concern companies by taking advantage of the § 3 Abs 2 AVRAG. The second topic is about the law of business pensions. Here, the main question that is discussed is, if the economic conditions of the parent company must be taken into account at the evaluation of the economic conditions of a concern subsidiary, when the concern subsidiary would like, for example, to reduce the business pensions. To find an answer to this question, a judgment of the OGH is discussed. The third topic is about the different existing possibilities, how the employees can be employed concern-wide. The focal point here is on the personnel leasing between different concern enterprises, respectively on the ?concern privilege?. Before the discussion of these three topics, some general aspects about concerns, for example which kinds of concerns exist, are discussed.