Iran's official news agency says Iraqi President Jalal Talabani arrived in Tehran to discuss bilateral relations.
The late on Thursday report by IRNA says Talabani will meet President Mahmoud Ahmadinejad and other leaders during his three-day visit.
Talabani last visited Iran in 2007.
The neighboring countries have had close relations after the 2003 overthrow of Iraqi dictator Saddam Hussein, who fought an eight-year war against Iran in the 1980s. The war left some one million casualties on both sides.
The United States has repeatedly accused overwhelmingly-Shiite Iran of using its influence in the majority-Shiite Iraq to fight US-led forces. Iran has denied the charge, saying the US occupation has caused security concerns there.