Sint-Maartenskerk or Sint-Maartenskathedraal (St Martin's Church or St Martin's Cathedral) is the former cathedral and seat of the former diocese of Ypres from 1561 to 1901.

Construction started on the church in 1230, and was finished in 1370. There had previously been a Romanesque church in the area, dating from the 10th or 11th century. Sint-Maartenskerk was heavily damaged during the World War I. Subsequently (1922–1930) the ruin was cleared and the church was entirely rebuilt following the original plans, although the tower was built with a higher spire than the original. With a height of 102 meters it is one of the tallest buildings in Belgium.