NMNHS is the only national institution directly engaged with the preservation of scientific collections of live and non-live nature from Bulgaria and the world. The study of biodiversity, environmental protection and the evolution of organisms are the museum’s major priorities. Consequently, the main task of NMNHS is the all-around study of the fauna, flora, fossils, minerals and rocks of Bulgaria and other countries. It develops the following scientific areas: taxonomy, faunistics, zoogeography and ecology of arachnids, myriapods, insects and all classes of vertebrates; taxonomy of fossil mammals, birds and brachiopods; floristics; mineralogy. Some of the areas have priority as a result of which NMNHS has become the national centre of biospeleology, archaeozoology and palaeontology of vertebrates and of bat studies. Insect studies are also highly developed.
Museum activities for maintenance of the exposition and its enrichment and the processing of scientific collections are performed along with the scientific studies. With this NMNHS is pursuing its educational and promotional mission. Yearly the museum is visited by some 50000 (in some years up to 115000) people. Students and pupils use its halls for practical seminars. Temporary exhibitions are organised. In the last years the topics of exhibitions have been: 120 Years of the Birth of Academician Ivan Buresch, Aconcagua Through the Eyes of a Zoologist, Rock Mysteries, Bulgarians on the Way to K2 Peak in Karakorum, 30 Years of Bulgarian Participation in UNESCO’s Program The Man and the Biosphere.