The river originates in the Koh-i Baba mountain range, part of Hindu Kush system, and follows a relatively straight course to the west.
In western Afghanistan the Hari Rud flows to the south of Herat. The valley around Herat was historically famous for its fertility and dense cultivation. The river meets the Jam Rud at the site of the Minaret of Jam, said to be the second tallest minaret in the world at 65 metres.
After Herat the river turns northwest, then north, forming the northern part of the border between Afghanistan and Iran. Further north it forms the south-eastern part of the border between Iran and Turkmenistan.
In Turkmenistan it is known as the Tedzhen river and it passes close to the city of Tedzhen.