Assyrians in Syria (Syriac: ܣܘܪ̈ܝܝܐ ܕܣܘܪܝܐ, Arabic: الآشوريون في سوريا) are an ethnic and linguistic minority indigenous to Upper Mesopotamia, the north-eastern half of Syria. Syrian-Assyrians are people of Assyrian descent living in Syria, and those in the Assyrian diaspora who are of Syrian-Assyrian heritage.

They live primarily in Al-Hasakah Governorate, with a significant presence in Hasakah city and the cities of Qamishli, Malikiyah, Ras al-Ayn, and Qahtaniyah, as well as in Tell Tamer and nearby villages. Some have migrated to Damascus and other western cities beyond the border of their indigenous Mesopotamia at the Euphrates River. They share a common history and ethnic identity, rooted in shared linguistic, cultural and religious traditions, with Assyrians in Turkey, Assyrians in Iraq and Assyrians in Iran, as well as with the Assyrian diaspora.

During the Old Assyrian Empire (2000–1750 BC), Middle Assyrian Empire (1365–1020 BC) and Neo Assyrian Empire (911–599 BC) much of, and often the entirety of the modern country of Syria, was under Assyrian rule, which founded in Northwestern Mesopotamia (modern-day Iraq). The northeastern part of the land became an integral part of Assyria proper during the 2nd millennium BC. Thus the presence of originally Akkadian-speaking and later Eastern Aramaic-speaking Assyrians in the northeastern part of the modern country dates back over 4000 years, where they lived alongside a diverse set of other peoples such as Hittites, Hurrians and Amorites throughout the ages. Traces of the long era of Assyrian settlement can be seen at numerous archaeological sites across the region. Important Assyrian cities in the region in ancient times include Til-Barsip, Carchemish, Guzana, Shubat-Enlil and Dur-Katlimmu.

The northeast of modern-day Syria was a part of Achaemenid Assyria (Athura) which was a geographical area within the Achaemenid Empire in Mesopotamia between 546 and 332 BC, then Seleucid Syria (312-150 BC), when the name Syria which was originally a 9th-century BC Indo-European corruption of Assyria and had hitherto referred only to Assyria itself, also became applied to a region long known as Aramea/Eber Nari. During the Parthian Empire (150 BC-224 AD) and early Sassanid Empire (224 -650 AD) (when the land was renamed Assuristan) a number of Neo-Assyrian kingdoms arose, and parts of northeast Syria became a part of the Neo-Assyrian state of Osroene until the mid-3rd century AD. Christianity became established amongst the Assyrians as early as the 1st century AD, and the region of Athura became the birthplace of Eastern Christianity and Syriac literature, with the Assyrian Church of the East and Syriac Orthodox Church being founded in the region.

After the Arab Islamic Conquest of the mid-7th century AD, Assyria/Athura/Assuristan was dissolved as a geo-political entity, and the region gradually saw an influx of Muslim Arab, Turkic and Iranic peoples. However, settlement in the northeastern areas often proved unsustainable in the long-term, leading to numerous episodes of population exodus. In addition to experiencing such destabilising factors such as climate shifts and over-cultivation of land, the area was also vulnerable to attack from nomadic peoples. Following the Mongol and Timurid invasions and subsequent massacre of Assyrians, it was left with only a scant permanent population. In the centuries that followed, a number of nomadic and semi-nomadic Arabic- and Kurdish-speaking tribes wandered the area with their livestock into the 20th century, when most of them were forced to settle by governmental policies.

When the Ottoman Empire conducted ethnic cleansing against its Christian populations, Kurds were responsible for most of the atrocities against Assyrians.^{[better source needed]} At the onset of the 20th century, Kurdish tribes cooperated with the Ottoman authorities in the genocides against Armenian and Assyrian Christians in Upper Mesopotamia. Many Assyrians from Hakkari settled in Syria after they were displaced and driven out by Ottoman Turks in the early 20th century. During the 1930s and 1940s, many Assyrians resettled in northeastern Syrian villages, such as Tel Tamer, Al-Qahtaniyah, Al Darbasiyah, Al-Malikiyah, Qamishli and a few other small towns in Al-Hasakah Governorate.

Most of the current population of Assyrians in Hasakah dates back to the French Mandate of Syria, when refugees from the now-Turkish areas north of present-day Syria (such as Tur Abdin) were settled together with displaced Armenians who had survived the Assyrian genocide and Armenian genocide in the area by the authorities as part of an effort to promote economic development. Given preferential treatment on the basis of their Christian religion by the French, they soon formed most of the new urban elite in the region. An additional influx of Eastern Assyrians began to resettle along the Khabur River in 1933 after the massacres of Assyrians in newly independent Iraq (see Simele massacre) forced the flight. These were refugees twice over—originally from the highlands of Hakkari, they had initially sought refuge amongst other Assyrians in Iraq in the face of the Assyrian genocide before the attacks.

In 1936, religious and political leaders—mainly from the Assyrian and Armenian Christian and Kurdish communities, with a few Arab groups as well—pressured the French authorities to give autonomous status to the Syrian Al-Jazira province (nowadays the Al Hasakah) for its mixed-ethnic population, like in the Sanjak of Alexandretta, the Alawite State, or Jabal al-Druze. The push for autonomy was marked by civil strife and inter-communal violence in the province, and angry hostility on the part of the mainly Arab nationalists pushing for outright independence for Syria. Long having viewed the settlement of Assyrians and Armenians in the country as the product of French colonialism, they were further incensed by the arrival of additional Assyrian refugees on the Khabur, and mobilized support from many Arab tribes and some Kurdish groups to counter the autonomists. The French forcibly cracked down on both sides as they grew increasingly violent, and the movement for autonomy soon failed. Later on, in 1957, the Assyrian Democratic Organization was set up in Syria by center-left intellectuals.