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
Progression‹See Tfd› PregolyaBaltic 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.