Turkish Prime Minister Recep Tayyip Erdogan arrived in Tehran on Tuesday evening on an official visit expected to be dominated by trade ties and the Syrian civil war.
The visit comes as the two countries are trying to rebuild relations strained by the situation in Syria, with Iran supporting President Bashar al-Assad while Turkey backs the rebels seeking to oust him.
Erdogan arrived late Tuesday, accompanied by his foreign, energy and economy ministers, Iranian media said.
He will meet Iran's President Hassan Rouhani, Foreign Minister Mohammad Javad Zarif and supreme leader Ayatollah Ali Khamenei, Iranian foreign ministry spokeswoman Marzihe Afkham said.
"Dialogue and contacts have entered a new phase, and we hope this trend continues. Besides serving the interests of the two countries, we hope (our dialogue) serve the interests of the region as well," Afkham said.
Rouhani will visit Turkey in the coming months, the ministry said.
Energy-hungry Turkey is planning to increase oil and gas imports from Tehran after the gradual lifting of sanctions on the Islamic republic's energy sector.
Iran reached an interim deal in November with world powers, under which it agreed to roll back parts of its nuclear programme and halt further advances in exchange for the release of billions of dollars in frozen assets and limited relief from crippling sanctions.
Before leaving Ankara, Erdogan told reporters he welcomed that agreement and hoped it would lead to a definitive deal on removing sanctions.
Signup to our newsletter and follow us on Facebook and Twitter!
"We wish the process will be finalised with an agreement that will ensure the removal of all sanctions on Iran. Turkey has so far done its best in that regard and will continue to do so," he said.
Turkish Foreign Minister Ahmet Davutoglu travelled to Tehran in late November and his Iranian counterpart Zarif visited Ankara earlier this month.
Erdogan also said he would raise the Syrian crisis during his visit.
"Turkey and Iran are two powerful countries that play a major role and have a say in the resolution of problems in the region," he said.
Erdogan is under the shadow of a massive graft scandal at home that includes illegal gold sales to Iran.
Iran has arrested a tycoon said to have been involved in the Turkish scandal.
Iranian officials say trade between the countries stood at $22 billion (16.2 billion euros) in 2012, before dipping to $20 billion in 2013. The figure is expected to reach $30 billion in 2015.
Five memorandums of understanding are expected to be signed during the trip.