Expressway S3 or express road S3 (in Polish droga ekspresowa S3) is a Polish highway, which runs from Świnoujście on the Baltic Sea through Szczecin, Gorzów Wielkopolski, Zielona Góra and Legnica, to the border with the Czech Republic, where it will connect to the planned D11 motorway.
The road was constructed from 2008 until October 2025. Its total length is 470.6 km (292.4 mi), but the last 3 km near the border remain closed to traffic until the connecting stretch of the D11 motorway is constructed in Czech Republic. This stretch is expected to be opened around 2026.
