The Russian Ministry of Defence (MoD) has directed the Russian Armed Forces deployed in Syria to return home.
Russian President Vladimir Putin said: "I think that the task that was assigned to the Ministry of Defence and the armed forces as a whole has achieved its goal, and so I order the defence minister to start tomorrow withdrawing the main part of our military factions from the Syrian Arab Republic."
According to the ministry, the first group of Russian planes left Hmeymim air base in Syria on Tuesday, followed by another set of aircraft that took off from the airbase in Khmeimim.
Russia is accused of helping Syrian President Bashar al-Assad, while the US-led coalition wants a neutral administration in the Middle Eastern country.
Senior adviser to Syrian President Bouthaina Shaaban was quoted by CNN as saying: "We were not surprised because the decision was made in coordination and consultation with us.
"We knew beforehand that this is what was going to be announced because the Russians came here to achieve certain jobs, and we and they agreed that most of the jobs have been achieved."
The US and Russia had entered an agreement over the cessation of hostilities plan in Syria, which is to be enforced from 27 February.
The two nations are co-chairs of the International Syria Support Group (ISSG) that aims at peaceful settlement of the Syrian crisis with support from the UN.
The countries agreed to jointly develop mechanisms to monitor the Syrian Government's and other force's compliance with the ceasefire.