A tiger subspecies inhabiting mainly the Sikhote Alin mountain region with a small subpopulation in southwest Primorye province in the Russian Far East. In 2005, there were 331–393 adult-subadult Amur tigers in this region, with a breeding adult population of about 250 individuals. The population has been stable for more than a decade due to intensive conservation efforts, but partial surveys conducted after 2005 indicate that the Russian tiger population is declining.

The Siberian tiger is the largest living felid and ranks among the biggest felids to ever exist.

Phylogeographic analysis with extant tiger subspecies suggests that less than 10,000 years ago the ancestor of Amur and Caspian tigers colonized Central Asia via the Gansu−Silk Road corridor from eastern China then subsequently traversed Siberia eastward to establish the Amur tiger population in the Russian Far East.

The Siberian tiger is reddish-rusty or rusty-yellow in colour, with narrow black transverse stripes. The body length is not less than 150 cm (60 in), condylobasal length of skull 250 mm (10 in), zygomatic width 180 mm (7 in), and length of upper carnassial tooth over 26 mm (1 in) long. It has an extended supple body standing on rather short legs with a fairly long tail. It is typically 5–10 cm (2–4 in) taller than the Bengal tiger, which is about 107–110 cm (42–43 in) tall.

The geographical range of Amur tigers in the Russian Far East stretches south to north for almost 1,000 km (620 mi) throughout the length of Primorsky Krai and into southern Khabarovsk Krai east and south of the Amur River. They also occur within the Eastern Manchurian mountain system, which crosses into Russia from China at several places in southwest Primorye. In both regions, peaks are generally 500 to 800 m (1,600 to 2,600 ft) above sea level, with only a few reaching 1,000 m (3,300 ft) or more. This region represents a merger zone of two bioregions: the East Asian coniferous-deciduous complex and the northern boreal complex, resulting in a mosaic of forest types that vary with elevation, topography and history. Key habitats for the Amur tiger are Korean pine broadleaf forests with a complex composition and structure. The ungulate complex is represented by red deer, wild boar, sika deer, roe deer, Manchurian moose, musk deer and ghoral.

A broad genetic sampling of 95 wild Russian tigers found markedly low genetic diversity, with the effective population size extraordinarily low in comparison to the census population size, with the population behaving as if it were just 27–35 individuals. Further exacerbating the problem is that more than 90% of the population occurs in the Sikhote Alin mountain region, and there is little movement of tigers across the development corridor, which separates this sub-population from the much smaller sub-population found in southwest Primorye province.

The winter of 2006–2007 was marked by heavy poaching. Poaching of tigers and their wild prey species is considered to be driving the decline, although heavy snows in the winter of 2009 could have biased the data.