Tammiku (Estonian: [ˈtɑmːikˑu]; German: Eichenhain) is a small borough in Jõhvi Parish, Ida-Viru County, in northeastern Estonia.

It is located about 3 km (2 mi) southwest of the town of Jõhvi and about 2 km (1 mi) northwest of Kohtla-Järve's Ahtme district.

[1] Tammiku was first mentioned as Damicas in 1241 in the Danish Census Book, and later as Tammykass in 1533 and Tammiku-Mõisaküla in 1945.

The name (in the genitive case) comes from the common noun tammik 'oak forest', referring to the local vegetation.

[2] Tammiku is the birthplace of Estonian amateur featherweight boxer Evald Seepere (1911–1990).