The Ileksa is a river in Onezhsky District of Arkhangelsk Oblast and Pudozhsky District of the Republic of Karelia in Russia. It is the principal tributary of Lake Vodlozero, and thus belongs to the basins of Lake Onega and of the Baltic Sea. It is 155 kilometres (96 mi) long, and the area of its basin 3,950 square kilometres (1,530 sq mi). The main tributary of the Ileksa is the Chusreka (left).