[1][2] The river takes its source under the name Zlata reka at an altitude of 2,054 m at 300 m southwest of the summit of Kapatnik (2,170 m) in the southwestern part of the Rila mountain range.

In its first 5 km it flows south a turbulent mountain stream until reaching the Predel Saddle (1,140 m) and turning west-northwest.

From there, along its whole course, the Gradevska reka forms the boundary between Bulgaria's highest mountain ranges, Rila in the north and Pirin in the south.

Until the village of Gradevo, where it takes its largest tributary, the Osenovska reka, it flows in a gently sloping forested valley, named Elovitsa.

Downstream of the village, the river valley widens and its slopes become deforested and eroded, while the riverbed is wide and filled with sediments.