The buses were traveling on the road between the capital Damascus and Deir Ezzor when the accident occurred.
The passengers on one bus belonged to the country's security service, according to state media, while the passengers on the other bus were civilians, according to the state news agency Sana, citing the Syrian interior minister.
About 30 people were reported injured.
The cause of the collision was not determined.
In a previous serious bus accident in Syria in July, when at least five people died, excessive speed was said to be the cause of the crash.
