Sintiki () is a municipality in the Serres regional unit of Central Macedonia, Greece. It covers an area of 1,103.431 km<sup>2</sup> and has a population of 18,544 according to the 2021 census. The seat of the municipality is the town of Sidirokastro.
Sintiki is named after Sintike, an ancient region and later district of the Kingdom of Macedon that was inhabited by the Sintians, a Thracian or possibly Pelasgian people.
The municipality was formed after the administrative reform in 2010 (Kallikratis plan) from the merger of the former municipalities of Kerkini, Petritsi and Sidirokastro and the rural municipalities of Agkistro, Achladochori and Promachonas. The administrative seat of the municipality is Sidirokastro. The former municipalities and rural municipalities have since formed the six municipal districts. The community is further subdivided into 3 city districts and 23 local communities.
The province of Sintiki () was one of the provinces of the Serres Prefecture. Its territory corresponded with that of the current municipality Sintiki, and a small part of the municipality Irakleia. It was abolished in 2006.