It connects Thessaloniki with Kavala, passing through Serres and Drama.

The section between Thessaloniki and Serres forms part of the Ε79 route.

The GR-12 runs north from downtown Thessaloniki as an urban arterial road called "odos Lagkada".

It passes through Lachanas and crosses the river Strymonas at Strymoniko.

It bypasses Serres, and runs east through Nea Zichni and to Drama.