The following thesis is an attempt to analyze the effect that has the Codes of Ethics for Museums within the other legal instruments; and answer questions like: Does a Code have a legal force? Is it addressed only to museums professionals, or is its scope wider? Furthermore there are presented two national organizations and one international that they have drafted Codes of Ethics for Museums and are recognized from the wider community that has to do with the protection of cultural heritage. These three organizations are the following: The Museums Association from United Kingdom, the American Association for Museums and the International Council of Museums. Within the framework of protection of cultural heritage and more specifically the protection of movable cultural objects from the illicit trafficking, there is an effort of a comparative study between these three Codes promulgated from the three organizations.