In the historical part one can find the first exhibits of the museum which were collected and prepared by Prof. T. Ivanauskas' father Leonardas Ivanauskas. These are Red-necked Grebe, Red throated Diver, Little Bustard, and Willow Grouse -birds stuffed in 1859 and 1861. Next to it the first and also the largest at the time in Lithuania collection of butterflies collected by entomologist Alfonsas Palionis. Biological groups of birds prepared during 1922-1939 are also presented. Further, the systematic collection begins.

Museums exposition starts with the most primitive animals: sponges, cnidarians, worms, molluscs, echinoderms, arthropods. More than 4 thousand of invertebrate animals are exhibited. In 2016 Vykintas Matuzevičius donated a collection consisting of more than 10 thousand shells.

About ten thousand insects belonging to more than 2 600 species are presented in the 24 stands of this hall. Besides the systematic exposition of insects, the zoogeographical distribution of butterflies is also presented. Australian, Ethiopian, Indomalaya and Holarctic regions are represented by the most colourful and most beautiful specimens of the Lepidoptera order. In separate stands are displayed the most spectacular and colorful beetles in the world. Also visitors can see two dioramas ("Useful insects of Lithuania" and "Insects in various biotopes"), a collection of wild Lithuanian bees (more than 140 different species) and a collection of Lithuanian butterflies (more than 400 species, gathered and donated by V. Bačianskas).

The representatives of three animal classes are displayed: fishes, amphibians and reptiles. The collection contains more than 7 thousand exhibits. The exposition contains about 500 exhibits. The most impressive exhibits are coelacanth, Atlantic sturgeon, swordfish, Indian python, caecilian, the only specimens of common sole and European hake caught in Lithuanian waters, sea turtles and crocodiles included in the IUCN Red List of Threatened Species.

Traditionally it is one of the best represented vertebrate classes in the museum. The collection contains more than 12 thousand exhibits; the exposition presents more than 900. stuffed birds and 600 eggs, belonging to 200 bird species. There are 12 dioramas in the exposition hall.

About 90% of all mammal species living in Lithuania are presented. In total, 365 stuffed animals, 3 moulages, 23 skulls, 5 dioramas, biological group of wisents. 55 species of presented mammals are listed in the IUCN Red List of Threatened Species (Cheetah, Siberian Tiger, Polar Bear, Snow Leopard, Giant Anteater, Bornean Orangutan and others), 14 species are listed in the Red Data Book of Lithuania. The exposition contains a whole range of animal "champions": the tallest animal in the world (giraffe), the fastest animal (cheetah), the largest predator (polar bear), and the smallest mammal (pigmy shrew)

About 300 trophies both from Lithuania and the rest of the world are displayed. These are horns, stuffed heads, sculls, furs, tusks. All the trophies are evaluated by the standard formulas for the measurement of trophies approved by the International Council for Game and Wildlife Conservation (CIC). One exhibit has been awarded the Grand Prix, 26 gold medals, 25 silver medals, 38 bronze medals. Most of the trophies are the catches of Lithuanian hunters.

Visitors can see skeletons of prehistoric and now living animals: skeleton parts of mammoths that lived in the territory of Lithuania more than 12 thousand years ago, horns of aurochs that wandered in our forests till the 16th century, skulls of woolly rhinoceros and the largest terrestrial mammal, the African elephant, some bones of the largest mammal in the world, the whale. In the anatomical part of exposition skeletons and skull models of mammals, birds, reptiles and fish are displayed.