Sumatran rhinoceroses were once quite numerous throughout Southeast Asia.
Fewer than 100 individuals are now estimated to remain.
The species is classed as critically endangered (primarily due to illegal poaching) while the last survey in 2008 estimated that around 250 individuals survived.
From the early 1990s, the population decline was estimated at more than 50% per decade, and the small, scattered populations now face high risks of inbreeding depression.
Most remaining habitat is in relatively inaccessible mountainous areas of Indonesia.

Poaching of Sumatran rhinoceros is a cause for concern, as the price of its horn has been estimated as high as US$30,000 per kilogram.
This species has been overhunted for many centuries, leading to the current greatly reduced – and still declining – population.
The rhinos are difficult to observe and hunt directly (one field researcher spent seven weeks in a treehide near a salt lick without ever observing a rhino directly), so poachers make use of spear traps and pit traps.
In the 1970s, uses of the rhinoceros's body parts among the local people of Sumatra were documented, such as the use of rhino horns in amulets and a folk belief that the horns offer some protection against poison.
Dried rhinoceros meat was used as medicine for diarrhea, leprosy, and tuberculosis. "
Rhino oil", a concoction made from leaving a rhino's skull in coconut oil for several weeks, may be used to treat skin diseases.
The extent of use and belief in these practices is not known.
Rhinoceros horn was once believed to be widely used as an aphrodisiac; in fact traditional Chinese medicine never used it for this purpose.
Nevertheless, hunting in this species has primarily been driven by a demand for rhino horns with supposedly medicinal properties.

The rainforests of Indonesia and Malaysia, which the Sumatran rhino inhabits, are also targets for legal and illegal logging because of the desirability of their hardwoods.
Rare woods such as merbau, meranti and semaram are valuable on the international markets, fetching as much as $1,800 per m³ ($1,375 per cu yd).
Enforcement of illegal-logging laws is difficult because humans live within or near many of the same forests as the rhino.
The 2004 Indian Ocean earthquake has been used to justify new logging.
Although the hardwoods in the rainforests of the Sumatran rhino are destined for international markets and not widely used in domestic construction, the number of logging permits for these woods has increased dramatically because of the tsunami.
However, while this species has been suggested to be highly sensitive to habitat disturbance, apparently it is of little importance compared to hunting, as it can withstand more or less any forest condition.

Nevertheless, the main cause of drastic reduction of the species is likely caused by the Allee effect.

The Bornean rhino in Sabah was confirmed to be extinct in the wild in April 2015, with only 3 individuals left in captivity.

The mainland Sumatran rhino in Malaysia was confirmed to be extinct in the wild in August 2015.

In March 2016 there was a rare sighting of a Sumatran Rhino in Kalimantan, the Indonesian part of Borneo.
The last time there was a Sumatran Rhino in the Kalimantan area was approximately 40 years ago.
This optimism was met with despair as that very specific Sumatran Rhino was found dead several weeks later after the sighting.
The reason of the death is currently unknown.

The Indonesian ministry of Environment, began an official counting of the Sumatran rhino in February 2019.
The track and tally exercise, was planned to be completed in three years.
Sumatran rhinoceroses were once quite numerous throughout Southeast Asia. Fewer than 100 individuals are now estimated to remain. The species is classed as critically endangered (primarily due to illegal poaching) while the last survey in 2008 estimated that around 250 individuals survived. From the early 1990s, the population decline was estimated at more than 50% per decade, and the small, scattered populations now face high risks of inbreeding depression. Most remaining habitat is in relatively inaccessible mountainous areas of Indonesia.
Poaching of Sumatran rhinoceros is a cause for concern, as the price of its horn has been estimated as high as US$30,000 per kilogram. This species has been overhunted for many centuries, leading to the current greatly reduced – and still declining – population. The rhinos are difficult to observe and hunt directly (one field researcher spent seven weeks in a treehide near a salt lick without ever observing a rhino directly), so poachers make use of spear traps and pit traps. In the 1970s, uses of the rhinoceros's body parts among the local people of Sumatra were documented, such as the use of rhino horns in amulets and a folk belief that the horns offer some protection against poison. Dried rhinoceros meat was used as medicine for diarrhea, leprosy, and tuberculosis. "Rhino oil", a concoction made from leaving a rhino's skull in coconut oil for several weeks, may be used to treat skin diseases. The extent of use and belief in these practices is not known. Rhinoceros horn was once believed to be widely used as an aphrodisiac; in fact traditional Chinese medicine never used it for this purpose. Nevertheless, hunting in this species has primarily been driven by a demand for rhino horns with supposedly medicinal properties.
The rainforests of Indonesia and Malaysia, which the Sumatran rhino inhabits, are also targets for legal and illegal logging because of the desirability of their hardwoods. Rare woods such as merbau, meranti and semaram are valuable on the international markets, fetching as much as $1,800 per m³ ($1,375 per cu yd). Enforcement of illegal-logging laws is difficult because humans live within or near many of the same forests as the rhino. The 2004 Indian Ocean earthquake has been used to justify new logging. Although the hardwoods in the rainforests of the Sumatran rhino are destined for international markets and not widely used in domestic construction, the number of logging permits for these woods has increased dramatically because of the tsunami. However, while this species has been suggested to be highly sensitive to habitat disturbance, apparently it is of little importance compared to hunting, as it can withstand more or less any forest condition.
Nevertheless, the main cause of drastic reduction of the species is likely caused by the Allee effect.
The Bornean rhino in Sabah was confirmed to be extinct in the wild in April 2015, with only 3 individuals left in captivity.
The mainland Sumatran rhino in Malaysia was confirmed to be extinct in the wild in August 2015.
In March 2016 there was a rare sighting of a Sumatran Rhino in Kalimantan, the Indonesian part of Borneo. The last time there was a Sumatran Rhino in the Kalimantan area was approximately 40 years ago. This optimism was met with despair as that very specific Sumatran Rhino was found dead several weeks later after the sighting. The reason of the death is currently unknown.
The Indonesian ministry of Environment, began an official counting of the Sumatran rhino in February 2019. The track and tally exercise, was planned to be completed in three years.
Sumatran rhinoceros