Tu Ky (Vietnamese: Tứ Kỳ) is a district (huyện) of Hải Dương Province in the Red River Delta region of Vietnam.
As of 2003 the district had a population of 167,664. The district covers an area of 168 km2 (65 sq mi). The district capital lies at Tứ Kỳ.
Coordinates: 20°49′59″N 106°22′59″E / 20.833°N 106.383°E