The HA postcode area, also known as the Harrow postcode area,[2] is a group of ten postcode districts in England, within seven post towns.

These cover part of northwest London, plus a very small part of south Hertfordshire.

The main sorting office is in Greenford (Green Park Way)[3] and the area served includes virtually all of the London Borough of Harrow, the northeastern part of the London Borough of Hillingdon, the western part of the London Borough of Brent and small parts of the London Boroughs of Barnet and Ealing, while the northern part of HA6 covers a small part of the Three Rivers district of Hertfordshire.

The approximate coverage of the postcode districts: