Mendon-Union High School was a public school in Mercer County, Ohio that mainly served an area that included the village of Mendon and Union Township.

The school and the district were closed following the 1991–92 school year[1] in a budgetary move and they were merged with the neighboring Parkway School District for 1992–93.

Parts of the district were also merged into St. Marys City Schools and Spencerville Local Schools.

[2] The Mendon-Union Pirates wore blue and gold while competing in the Midwest Athletic Conference.

This Mercer County, Ohio school article is a stub.