National Road 1 (alternatively marked as M-1, M1 and M 1), was a road in Serbia, connecting Croatia at Batrovci with North Macedonia at Tabanovce.

The route was a part of a notably larger motorway which existed during SFR Yugoslavia, generally known as Brotherhood and Unity Highway (Serbian: Аутопут "Братство и јединство"/ Autoput "Bratstvo i jedinstvo"; Croatian: Autocesta "Bratstvo i jedinstvo"), therefore considered as the most important route in Serbia.

After the new road categorization regulation given in 2013, the route bears designations A3 and A1.

[1][2] The road was a dual-carriageway motorway.