Delivering biopharmaceuticals across mucosal surfaces may offer several advantages over current injection techniques. Therapeutic efficacy may be increased, and patients are likely to favour methods that do not require injections. At an IIR Ltd meeting, ‘Successfully Exploiting the Commercial Potential of Drug Delivery Systems for New and Existing Therapeutics’ [London, UK; January 1995], Professor Lisbeth Illum from DanBioSyst UK, outlined some of the problems and solutions encountered in studies of the transmucosal delivery of polypeptide biopharmaceuticals.