Boddington's and XXXX have seen a gradual decline in adspend in recent years. According to Nielsen, the two brands spend £1.9m and £1.8m, respectively.
It is unclear whether the brewer will award the brands to other InBev roster agencies, including Leo Burnett and Lowe London, or put them up for pitch.
BBH has produced some of its most memorable advertising for the Boddington's brand, including the introduction of the "The Cream of Manchester" and "It's a bit gorgeous" lines. A relaunch campaign for the bitter starring the model Melanie Sykes made her a household name.
The agency has handled Castlemaine XXXX since the end of 2003.
Ben Fennell, the BBH managing director, said: "We wish InBev a very fond farewell and are proud of our award winning recent campaigns for Murphy's and Boddingtons. It's good to go out on a high."
A spokesman for InBev said: "BBH has been a fantastic creative agency and we are delighted to have had the opportunity to work with it."
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