The Modruš-Rijeka County (Croatian: Modruško-riječka županija; Hungarian: Modrus-Fiume vármegye) was a historic administrative subdivision (županija) of the Kingdom of Croatia-Slavonia. Croatia-Slavonia was an autonomous kingdom within the Lands of the Crown of Saint Stephen (Transleithania), the Hungarian part of the dual Austro-Hungarian Empire. Its territory is now in western Croatia. Modruš is a small town near Ogulin; Rijeka is a large city on the Adriatic coast.