Hydrangea serrata is a species of flowering plant in the family Hydrangeaceae, native to Japan and Korea. It is a deciduous shrub that typically grows to 1-3 m tall and wide. The leaves are ovate to elliptic, 5-12 cm long and 3-8 cm broad, with a serrated margin. The flowers are produced in flat corymbs 6-12 cm diameter in early summer, with a lacecap-like arrangement of sterile flowers surrounding a central cluster of fertile flowers.