The department's collections accomodate the sections: zoology, botany, geology, mineralogy, palaeontology and ethnographica. Staff members and private contributers (especially members of the Nassau Society for Natural Science) tend and develop the collections since 1829. Today's stock of natural objects is one of the fifteenth most important collections in Germany. Many scientists have worked on the collections. This has contributed to a large number of "types", which are tended with particular attention. The year-books of the society document most of the collections. There is a detailed index register on the internet.

The majority of the objects are documented in catalogues and on index cards. We will try to transfer this database to the computer in the next years. Extensive gaps exist in the documentation of the geological collections. Therfore the correct number of available objects can only be estimated (approximately 1,3000,000).

Due to the administration of the museum by the Nassau Society of Natural Science the emphasis of the museum's collecting activities lay on the documentation of the former duchy of Nassau. But with colonization a lot of material came from regions all over the world. Since the middle of the 19th century, scientific collections developed by purchasing complete private collections.