The Ukrainian Catholic Eparchy of Saint Nicholas of Chicago is a Ukrainian Greek Catholic Church ecclesiastical territory or eparchy of the Catholic Church in the whole Western United States and Midwest, Alaska, and Hawaii. As of 2020, the St. Nicholas Eparchy has 43 churches and missions in the western USA.

St. Nicholas Cathedral is a Ukrainian Greek Catholic cathedral located in the Ukrainian Village neighborhood of Chicago, Illinois, United States. It houses the seat for the Eparchy of Saint Nicholas of Chicago.