There are seven UNESCO conventions on the safeguarding of culture and cultural heritage. While four of these conventions focus on the protection of tangible heritage, the other three conventions are devoted to the safeguarding of intangible cultural heritage. Among these conventions, one regarding the tangible and the other on intangible heritage have international heritage lists. The preliminary examination of the nomination files proposed to the heritage lists is made by consultative institutions and bodies which deliver their advisory opinions to the related Committee. ICOMOS in the field of cultural heritage, IUCN in the field of natural heritage and ICCROM in the field of preservation and restoration have undertaken the responsibility to present their opinions on the files with regard to 1972 Convention. As to 2003 Convention, instead of such international or intergovernmental institutions, advisory mechanism for nomination processes have been formed with three transitory structures as Subsidiary Body, Consultative Body and Evaluation Body. While Subsidiary Body examined nomination files proposed to the Representative List between 2008-2014, Consultative Body analyzed nomination files on Urgent Safeguarding List, Register of Good Safeguarding Practices and International Assistance Requests between 2010-2014. Thereafter, this dual structure was abandoned in 2014 and a new advisory body was formed by the name Evaluation Body. The fact that the advisory bodies of 1972 Convention are international or intergovernmental institutions might, on the one hand, facilitate the transmission of institutional memory and experiences among experts, on the other hand, this might lead to authoritativeness. Occasionally, there might arise some divergences between advisory bodies and World Heritage Committee, which is the decision maker for inscriptions to the list, or state parties proposing their files. Nevertheless, these conflicting fields haven't damaged the valuableness of the World Heritage List yet. In the case of 2003 Convention, election of the members of advisory bodies according to quotas and balances and inability of each member to serve more than two or four years hinder the formation of institutional memory and transmission of experiences. On the other side, it is possible to elect experts who aren't competent enough academically or scientifically or don't have the knowledge of the Convention due to the fact that 6 members are elected on behalf of their governments out of 12 members and the rest six members are the representatives of NGOs. Therefore, this might cause some disputes over the accuracy of advises and on the other hand, it might give way to frailty of authority as it may not be possible to hold the efforts of the committee members to include the elements with unfavorable opinion in the list. In order to prevent this, the inclusion of universities, research centers, institutes, UNESCO chairs and Category 2 Centers into advisory mechanisms may be proposed. Furthermore, in contrast to 2003 Convention, 1972 Convention have the mechanism enabling the experts to see the heritage sites in situ. For this reason, accuracy rate of the advises go down. So that, instead of evaluation of files, evaluation of heritage in situ might be more beneficial. Thus, a strong and assuring advisory mechanism might contribute more to the valuableness of the Convention and credibility of the lists.