The Deleynska reka (Bulgarian: Делейнска река) is a river in northwestern Bulgaria, a left tributary of the Topolovets, itself a right tributary of the Danube.

[1] The river takes its source on the Bulgaria–Serbia border at an altitude of 328 m in the northwesternmost part of the Balkan Mountains, some 1.5 km northwest of the village of Rabrovo.

The river flows in direction northeast and east, before bending to the southeast at the village of Tiyanovtsi.

It flows into the Topolovets at an altitude of 37 m about 2.3 km northwest of the city of Vidin.

[1] Its drainage basin covers a territory of 102 km2, or 17.4% of the Topolovets's total.