Virgin Trains East Coast has cut 150,000 fares in a sale running from today (Tuesday) until Friday.
Reduced prices start at £10 to and from London to Leeds or York, £15 to Newcastle and £20 to Edinburgh.
Discounted first class tickets cost £25 to and from the two stations in Yorkshire, £35 to Newcastle and £40 to the Scottish capital.
The deals cover travel from September 5 to November 13, excluding September 26-27; October 3, 4, 9 and 10; and October 23 to 1 November 1.
The train firm’s head of marketing, George Shuttlewood, said: “This is your chance to save big on travel between London and Edinburgh, and everywhere we go in between. And with over 150,000 seats available over the travel period, there’s lots of choice.
“London is always the most popular destination, but with prices so low it’s the perfect opportunity to try somewhere new or take a trip to visit family and friends.”