The business last came up for review in 2004, when the account was handed to Bartle Bogle Hegarty. However, the agency has not created any work for the client.
The bookmaker is looking to begin advertising again in 2006 as it extends its business focus beyond the traditional horse-racing bets into the online gambling market, including internet betting and online poker.
The move to appoint a new creative agency follows last October's appointment of Claydon Heeley Jones Mason to its £10 million through-the-line account.
In January this year, Ladbrokes also instigated a nationwide rebranding of its retail network, including a reworking of the signature red-and-white emblem that is used across its network of 1,900 betting shops.
The new logo will initially be introduced to new shops, then applied to the older outlets once they have been refurbished.
The updated brand will be communicated through in-store point-of-sale material and through Ladbrokes' own online and digital television presence.
It will eventually be extended across the entire chain to create a unified brand image.
Ladbrokes faces stiff competition from other online betting and gaming sites such as Betfair, William Hill and Poker.com.
Leo Burnett declined to comment on the story.