The present thesis aims to define the concept of “extraordinary circumstances” ac-cording to prevalent passengers rights of the European Community. Based on the assumption of extraordinary circumstances being problematic to interpret, Regulation (EC) no 261/2004 (air passenger rights) as well as the practical use of extraordinary circumstances under Regulation (EC) no 1371/2007 (rail passenger rights), Regulation (EU) no 1177/2010 (ship passenger rights) and Regulation (EU) no 181/2011 (bus and coach passenger rights) shall be analyzed and discussed. Regulation (EC) no 261/2004 lacks the definitions of essential terms which gives room for discussions on how to interpret these correctly. Particularly, the inclusion of technical problems under the concept of extraordinary circumstances is a decisive issue. Also, bad weather conditions or strikes could be identified as problematic to mention as extraordinary circumstances. Since the regulation entered into force, various court proceedings have resulted in what could not be any more different. While the interpretation of extraordinary circumstances was found highly problematic under the air passenger rights regulation, the regulation on rail passenger rights no longer listed such exceptions in 2007. Regulation (EC) no 1371/2007, however, has also been criticized for its wording with regard to potential grounds for relief of liability. In addition to the regulations already mentioned, the present thesis deals with regulations on ship passenger rights and bus and coach passenger rights focusing on arguments that transport companies can put forward in case of extraordinary circumstances.