The Heathrow Express service will stop running for 36 hours over the August Bank Holiday weekend to allow Network Rail to do work on the Crossrail project.
Trains will stop from 0001 on Saturday August 23 until 1225 on Sunday August 24.
At the same time, the Heathrow Connect stopping service will also be partly suspended, running only between Paddington and Hayes and Harlington.
Travellers will have to use the 140 bus to travel on from Hayes and Harlington to Heathrow, which will be free of charge.
"We recognise this is not good timing for people planning to travel between Heathrow and Central London over the Bank Holiday weekend," said Keith Harding, operations director for Heathrow Express.
"We hope, by giving our customers plenty of prior warning, we can help them continue with their travel plans without too much hassle.”
The Piccadilly Line, which serves all Heathrow terminals, is due to run as normal.
