Tadmor prison (Arabic: سجن تدمر‎) is located in Palmyra in the deserts of eastern Syria approximately 200 kilometers northeast of Damascus (Tadmor, or Tadmur is the Arabic name for Palmyra).

The structures were originally built as military barracks by the French Mandate forces.

Tadmor prison was known for harsh conditions, extensive human rights abuses, torture and summary executions.

During the 1980s Tadmor prison housed thousands of Syrian prisoners, both political and criminal and it was also the scene of the June 27, 1980 Tadmor Prison massacre of prisoners by Rifaat al-Assad, the day after the Syrian branch of the Islamist Muslim Brotherhood failed in an attempt to assassinate his brother, president Hafez al-Assad. Members of units of the Defence Brigades, under the command of Rifaat al-Assad, entered Tadmor Prison and killed an estimated thousand prisoners in the cells and the dormitories. Tadmor prison was closed in 2001 and all remaining political detainees were transferred to other prisons in Syria.

Tadmor Prison was reopened on June 15, 2011 and 350 individuals arrested for participation in ani - regime demonstrations were transferred there for interrogation and detainment.

The Tadmor Prison Massacre (Syria) occurred on 27 June 1980, the day after a failed attempt to assassinate Syrian president Hafez al-Assad. Members of the units of the Defense Companies, under the command of Rifaat al-Assad, brother of the president, entered into Tadmor Prison and massacred about a thousand prisoners in the cells and the dormitories.