The event, whose title backer Flora is often cited by analysts as one of the best examples of sponsorship investment, will now remain on the BBC and BBC Radio Five Live up to and including 2005.
Dominic Coles, director of rights and finance for BBC Sport, comments: "The London Marathon is more than just a race, it is a defining event which is both a world-class professional race and a massive fund-raiser."
The new rights deal also includes coverage of the Flora Light Challenge for Women - a 5km run through London's Hyde Park involving UK television celebrities running alongside a selection of professional athletes.
The BBC has broadcast the London Marathon since its conception in 1981, with this year's race attracting 5.5 million viewers to the five hours of live coverage provided by the broadcaster.
