Union leaders claim hundreds of night buses face the axe to pay for London's new 24-hour Underground service.
The 'Night Tube', which starts in September, is expected to lose millions of pounds in its first few years.
Transport for London has admitted night bus services are under review to avoid a duplication of routes.
The TSSA union believes almost a third of the capital's night bus routes could disappear.
The union says its analysis reveals 47 out of 167 routes run in parallel with the Central, Jubilee, Piccadilly, Northern and Victoria Lines.
Transport for London said it was planning a public consultation on the changes to the night bus network.