Mersin İdmanyurdu (also Mersin İdman Yurdu, Mersin İY, or MİY) Sports Club; located in Mersin, east Mediterranean coast of Turkey in 1977–78. The 1977–78 season was the sixth season of Mersin İdmanyurdu (MİY) football team in First League, the first level division in Turkey. They have relegated to second division at the end of the season. It was the second relegation from first division after 1973–74. Team's bad performance continued in Cup matches as well.