The Iskander Darya (Russian: Искандердарья; Tajik: Искандардарё) is a river in Ayni District of Sughd Region, Tajikistan. The Iskander Darya is 20 kilometres (12 mi) long, and the area of its drainage basin is 950 square kilometres (370 sq mi) long. It is the left source river of the Fan Darya.

The Iskander Darya has its source in Lake Iskanderkul and flows east. The mouth of Iskander Darya is near the village of Zarafshan II. The river merges with the Yaghnob at an altitude of around 1640 m, forming the Fan Darya.