Heart's business has been with Elliott Borra Perlmutter for eight years.
The agency has been invited to pitch along with at least two other unnamed agencies.
The brief is aimed at increasing the station's share of female listeners as it does battle with 95.8 Capital FM's Johnny Vaughan breakfast show.
The AAR is handling the process.
EBP's most recent TV work was for the Jono Coleman and Harriet Scott breakfast show, which ran against the launch ads for Vaughan's show.
The review is being overseen by the Heart marketing director, Steve Parkinson, and is in its early stages, with chemistry meetings taking place this week. Media, which is with Starcom Mediavest, is unaffected.
Last year, EBP ran a series of ads aimed at recruiting female listeners in their twenties and thirties to Heart. One spot featured four girls in a car singing along to their favourite pop songs.