The Irgiz (Kazakh: Ыргыз Yrgyz; Russian: Иргиз) is a river in Aktobe and Kostanay regions of Kazakhstan, a right tributary of the Turgay.

[1] It was the site of the Irghiz River skirmish in the early 13th century.

The Irgiz rises on the eastern slopes of the Mugodzhar Hills in the Aktobe region of Kazakhstan.

It flows in a predominantly southerly direction to its confluence with the Turgay.

Its main tributary is the 178 km (111 mi) long Chet-Irgiz (Шет-Иргиз) from the right.