This report presents an initial analysis of the present situation with regard to serial (and transnational serial) natural properties inscribed in the UNESCO World Heritage List. It is primarily based on the information included in the nomination dossiers and evaluation reports for these properties, as included on the website of the UNESCO World Heritage Centre (whc.unesco.org). The document was originally prepared, in draft, as an input to the seminar on “Serial and transnational Natural World Heritage Properties” held from 26th-30th November 2008 at the International Academy for Nature Conservation, Isle of Vilm, Germany. The report is not a policy statement but rather aims to summarize the current range of serial natural World Heritage Properties and the parameters.