The museum houses the largest zoological collection in Lithuania, with about 300,000 specimens of various zoological preparations: stuffed animals, skeletons, skulls, study skins, fluid-preserved specimens, eggs, mummified (dry) specimens etc. From tiny scale insects to giraffes. One part of the collection is for teaching objectives (exhibition, demonstration), another one - for purposes of scientific research. The collections are divided into groups: mammal collections - 8,000 specimens; avian collections - 12,000; herpetology collections – 3,700; fish collections - 3,400; invertebrate collections - 56,000; entomology collections - 202,000. The most valuable collections: the beetle collection of K. Aris "Coleoptera Palearctica", the conchology collection of V. Matuzevičius, and the collection of animal type specimens.