The Litani River (Arabic: نهر الليطاني, Nahr al-Līṭānī), the classical Leontes (Greek: Λέοντες, Léontes, lit. "Lions"), is an important water resource in southern Lebanon. The river rises in the fertile Beqaa Valley, west of Baalbek, and empties into the Mediterranean Sea north of Tyre. Exceeding 140 km in length, the Litani River is the longest river in Lebanon and provides an average annual flow estimated at 920 million cubic meters. The waters of the Litani both originate and flow entirely within the borders of Lebanon. It provides a major source for water supply, irrigation and hydroelectricity both within Southern Lebanon, and the country as a whole.
Sections of its lower reaches were under Israeli control during 1978 and from 1982 to 2000.
After heading south parallel to the Syrian border, as the Litani nears northern Israel, the course of the river bends dramatically westward. Near this bend, the Litani comes within five km of the Hasbani River and four km from the Israeli border.
The portion of the river flowing west is called the Qasimiyeh. The Qasmieh-Ras-el-Aïn region, irrigated from the river's lower reaches from main irrigation canals, to south and north, is one of the largest irrigated areas in the nation, consisting of 32.64 km², shared among 1257 irrigating farmers, who concentrate on citrus crops and bananas (Raad 2004). For the entire stretch of the Qasimiyeh as it flows into the Mediterranean Sea, the Litani River remains nearly parallel to (and about 29 km (18 mi) north of) the Israeli-Lebanese border. 10 km north of Tyre, the river is crossed by the ancient Leontes Bridge. In June 1941, the mouth of the river was the site of an attack by British commandos and Australian troops on Vichy French forces that became known as the Battle of the Litani River.