The health charity is looking to re-engage lapsed supporters and those who have requested information.
Jane Moore, account director at DMS, said: "Central to the campaign will be understanding the audiences' connection to the cause and motivations for engaging with Asthma UK."
The campaign is set to launch in March 2009.
Mel Oley, assistant director of Individual Giving at Asthma UK, said: "We appointed DMS based on our chemistry, as well as their experience in delivering effective campaigns to engage supporters."