Háj ve Slezsku (Czech pronunciation: [ˈɦaːj ˈvɛslɛsku]; German: Freiheitsau), is a municipality in Opava District in the Moravian-Silesian Region of the Czech Republic. It has around 3,300 inhabitants. It lies between Opava and Ostrava.
Háj ve Slezsku is made up of villages Chabičov, Háj, Jilešovice, Lhota and Smolkov.
The name of the municipality means "grove in the Silesia".
First settlements in the area were probably established in the 13th century, however the first mention about a village here is from 1366. The youngest village is Háj, which was established in 1784 as a part of Chabičov. It was considered its administrative part until 1922. By the unification Chabičov, Háj and village of Smolkov, it officially became an independent municipality, and the three villages became administrative parts. Since 1970 the municipality is called Háj ve Slezsku. Jilešovice and Lhota were incorporated in 1976 and 1979, respectively.
For several years the town has celebrated its citizens and people from surrounding areas in an annual festival called Rozmarné léto, after the best known novel of Vladislav Vančura.