Hoogezand-Sappemeer is a former municipality in the Northeastern Netherlands. It was the third most-populous municipality in the province of Groningen, after Groningen and Oldambt. It was formed in 1949 by the merger of the former municipalities of Hoogezand and Sappemeer. On 1 January 2018, Hoogezand-Sappemeer merged with Slochteren and Menterwolde, forming the new municipality Midden-Groningen.