Coordinates: 42°37′50″N 23°15′17″E / 42.63056°N 23.25472°E
The Boyanska reka (Bulgarian: Боянска река, "Boyana river") is a river in western Bulgaria, a tributary to Vladayska River.
The river flows from the northern slopes of Cherni Vrah on Vitosha Mountain, crossing Torfeno Branishte Nature Reserve; at the northern foothills of Vitosha the river drops forming the Boyana waterfall and then crosses the village of Boyana (part of Sofia, from which the river takes its name) to flow into Vladayska River in the Sofia district of Ovcha Kupel.