The Islamic Republic of Iran and the Republic of Iraq share a land boundary that extends for 1,671 kilometers (1,038 miles). Beginning at a point in the Shatt al-Arab waterway in the south, the boundary follows the thalweg of the river northward, eventually meeting and continuing along the western foothills of the Zagros Mountain Range before ending at the tripoint with Türkiye at Kuh-e Dalanper. The modern-day boundary has its basis in the Constantinople Protocol of 1913, agreed to by then Persia and the Ottoman Empire, who controlled much of Iraq at the time.

In 1975, Iran and Iraq reaffirmed the historic boundary delimitation in a “Treaty of Good Neighbourliness,” which established the demarcation of the frontier. While the 1975 Agreement was meant to settle all ongoing conflicts between Iran and Iraq, tensions continued between the two States. In 1980, Saddam Hussein proclaimed that Iraq would no longer recognize the validity of the 1975 Treaty. An eight-year war broke out shortly thereafter, reintroducing further turmoil in the region. The conflict ended with both States agreeing to United Nations Resolution 598, which required them to pull their forces back behind the internationally recognized boundary from 1975.

Following the Iraq–Iran War, conflict over the land border was overshadowed by the United States invasion of Iraq in 2003. Few major developments occurred between Iraq and Iran over the land boundary until the President of Iran met with leadership in Iraq in March 2019. During this visit, the Iraqi and Iranian leadership discussed and signed a number of memorandums of understanding concerning oil, trade, health and easing visa restrictions for citizens between their two States. As part of this momentous meeting, Iran and Iraq announced their intention to begin the re-implementation of the 1975 boundary agreement. This would include dredging the Shatt al-Arab waterway to restore it to its course in 1975 to better align with the international boundary.

Disputes over water rights and freedom of navigation in the Shatt al-Arab, among others, still persist between Iraq and Iran. However, in recent years, the States have shown increasing willingness to conduct negotiations over security issues, signing two border security agreements in 2023 and 2025.