The road starts just west of Saxilby where it branches of from the A57 from Lincoln. It heads northwest through the village of Fenton. The A1133 from Newark-on-Trent merges with the road slightly further on where it makes a sharp turn and heads north alongside the River Trent and the border with Nottinghamshire. Further on at Marton the A1500 joins from the east. The A156 continues on to Lea where the B1241 joins from Saxilby then the road heads into Gainsborough where it terminates just south of the centre at the A631. The A159 continues north from here through the town centre and north to Scunthorpe.