Starting from today (Thursday), a tree-planting scheme is set to transform the street - which is famous for being a centre of medical expertise - into a green haven.
A total of 45 Chanticleer pear trees are being planted in the £13,500 facelift covering the entire length of Harley Street.
The trees have been chosen for their resistance to disease and narrow growth that will avoid causing problems for the street's historic buildings.
The planting, run by Westminster City Council, is expected to take less than a week. A ceremony is planned for 19 March, to be attended by the Duchess of Devonshire and Lord Mayor of Westminster.