This paper discusses the issue of whether investors who raise claims on grounds of a violation of BIT obligations by the state may take recourse to the most favoured nation clause with respect to the jurisdiction of the arbitration tribunal. Case law and scholarly literature provide divergent opinions regarding this question. The case law in the form of previous arbitral awards shows that most arbitration courts have been inclined to permit such recourse in cases in which investors invoked the MFN clause because they wished to avoid procedural requirements which would have resulted in substantial protractions for the arbitration procedure. Conversely, arbitration courts have refused (with one single exception) to allow the “import” of new arbitration clauses into the main contract. Part I of the paper provides an overview of the issue, and offers reasons for the existence of such highly divergent positions. Part II describes the existing relevant jurisprudence. Part III analyses the most recent award in Austrian Airlines vs. Slovakia. The authors also attempt an assessment (in Part IV) whether the cited award might lead to a more consistent administration of justice in this area, and thus make arbitration in investment treaty cases more predictable.