The invention provides a method for combating biofilm, said method comprising contacting a biofilm with an alginate oligomer. The biofilm may be on an animate or inanimate surface and both medical and non-medical uses and methods are provided. In one aspect the invention provides an alginate oligomer for use in the treatment or prevention of a biofilm infection in a subject. In another aspect the method can be used to combat biofilms, on abiotic surfaces, e.g. for disinfection and cleaning purposes.
