The Instruch (Russian: Инструч; German: Inster; Lithuanian: Įsrutis, Įsra; Polish: Wystruć) is a river in Russia's Kaliningrad Oblast. It begins northeast of Dobrovolsk and, along with the river Angrapa, forms the Pregolya near Chernyakhovsk.

Instruch
Map
Location
CountryRussia
Physical characteristics
Mouth 
 • location
Pregolya
 • coordinates
54°38′52″N 21°47′27″E / 54.64778°N 21.79083°E / 54.64778; 21.79083
Basin features
ProgressionPregolyaBaltic Sea

Prior to 1945, the river was part of German East Prussia. The town of Insterburg (now Chernyakhovsk) was named after the river's German name, Inster.