Richard Beaven, chief executive of Initiative North America, said: "This is both a testimony to the great work Initiative has done for Bayer over the years and an acknowledgement of our capability to deliver end-to-end solutions."
Bayer HealthCare's brands include Alka Seltzer and Aspirina.
The agency's new business wins over the past year include CBS, Showtime, Lionsgate Films and Gateway the computer manufacturer.