It flows out of the Valdai Hills and continues west into the Daugava (Western Dvina).

The town of Nelidovo and the urban-type settlement of Zharkovsky are located along the Mezha.

Its main tributaries are the Bereza, the Luchesa, the Obsha, and the Yelsha (all left).

It flows south, downstream of the town of Nelidovo, turns southwest and crosses into Zharkovsky District.

The mouth of the Mezha is the triple point where Tver, Smolensk, and Pskov Oblasts meet.