Žagarė Regional Park is one of the smallest in Lithuania. It was established to protect the Švėtė sub-valley and Žagarė Forest landscape as well as other natural and cultural heritage values:

• Žagarė and the surrrounding landscape, and the clearly visible Gaudikiai moraine ridge;
• Cultural heritage values such as the old Žagarė urban complex with the original church constructed from local stone, a manor site, the Žvelgaitis castle mound archeological complex, as well as the town‘s Baroque church, unique clay brick presbytery, the Žagarė manor emsemble, a unique stud farm, wind mill, park and Raktė castle mound;
• The stability of the natural ecosystem, its biotic components, characteristic flora and fauna, botanically valuable forests with rare plant communities, rare plant habitats, and important water bird nesting grounds and migratory rest stops

The regional park is characterised by the morphological structure created by the medium sized river valley hydrological processes with the adjoining Žagarė forest massifs and the distinctive western strip of the Northern Lithuania (Linkuva) morainic ridge. The landscape diversity of the Žagarė Regional Park has been created by the following major landscape types: forested morainic plains, cultivated morainic plains, forested sandy glaciolacustrine plains, forested sandy glacio-fluvial plains, cultivated morainic hill-ridge, little cultivated shallow valley, urbanized morainic sub-valley, little forested cultivated and little urbanized meandering valley, forested swampy complexes and plains, natural and channelled rivers, ponds and complexes thereof, urban developments of the landscape, and manufacturing as well as quarry extractive complexes.

These are the territories of European Community importance (code, title) found in the park: 9020 Fennoscandian hemiboreal natural old broad-leaved deciduous forests (Quercus, Tilia, Acer, Fraxinus or Ulmus) rich in epiphytes, 9080 Fennoscandian deciduous swamp woods.

The total number of plant species is 1042 of which 2 are protected by the European Community, and 24 are included in Lithuania’s Red Data Book. The total number of animal species is 443. Mammals – 42 species, of these 11 are protected by the European Community, and 3 are included into the Lithuania’s Red Data Book. Birds – 150 species, of these 33 are protected by the European Community, and 26 are included into the Lithuania’s Red Data Book. Fishes – 13 species, of these 2 are protected by the European Community, and 1 is included into the Lithuania’s Red Data Book. Amphibians and reptiles – 13 species, of these 4 are protected by the European Community, and 2 are included into the Lithuania’s Red Data Book. Invertebrates – 227 species, of these 12 are protected by the European Community, and 21 are included into the Lithuania’s Red Data Book.

The following zones have been established in the Žagarė Regional Park to protect its natural and cultural heritage values: 8 reserves (1 geomorphological, 4 botanical, 1 botanical-zoological, 1 telmological, and 1 urban).

Gaudikiai Geomorphological Reserve has been established to protect the distinctive Gaudiškiai morainic ridge – a fragment of the Linkuva morainic ridge.

The botanical reserves have been established to protect: Didmargis – the communities of spruce forests with oaks and ash trees characteristic to the Northern Lithuania plains, and growing sites of the protected plants – Astrantia major, Cypripedium calceolus; Dilbinėliai – the growing sites of the protected plants – Astrantia major, Cypripedium calceolus; Pabaliai – the communities of Seslerietum uliginosae, Carex paniculata, Molinietum caeruleae, and the growing sites of Dactylorhiza baltica, Astrantia major; Švėtė – the growing sites of the protected plants Astrantia major, Pinguicula vulgaris, Sesleria caerulea.

The Žagarė Botanical-Zoological Reserve has been established to protect spruce forests with additions of oak, ash, linden and elm typical to the plains of north Lithuania; the abundant and varied fauna and one of the most abundant populations of Cypripedium calceolus in Lithuania. 

The Mūšos tyrelis Telmological Reserve has been established to protect a part of the Mūšos tyrelis raised bog, and the surrounding forests.

The Žagarė Urban Reserve has been established to protect the urban structure (layout, spatial and volumetric composition) of the historical part of the Žagarė town retaining its specific features, the authentic or traditional type of territory and individual land plot development, the traditional architectural expression, connection with the natural environment, the old town area, the Žagarė manor estate, Žagarė and Raktuvė mounds with the settlements, and other values of cultural heritage with the surrounds.

There are 7 objects of natural heritage in the Žagarė regional park: Švėtės exposure, Tyrelis stone, Žagarė exposure, Švedpolis spring, Žagarė esker (natural monument), Žagarė forest Pinus strobus, and the Žagarė rowan. There are 39 cultural heritage objects in the park.