This thesis describes the role of internet-based support in the delivery of an asthma self management program. First, the compliance and reliability of home lung function monitoring, one of the key features of asthma self-management, was studied and appeared to be high over a 4-week period. Second, we explored intrinsic barriers to current asthma management and revealed possible benefits from internet-based asthma self-management. Participants considered feasible electronic monitoring, easily accessible information, e-mail communication and the use of an electronic action plan to be the main benefits of internet-based asthma self-management. Third, we assessed the clinical effectiveness and cost effectiveness of an internet-based asthma self-management program over a period of 1 year. Internet-based self-management improved asthma related quality of life, asthma control, symptom-free days and lung function, but did not decrease the number of exacerbations. The benefits gained were attained at reasonable costs from a societal perspective and even more so from a health care perspective.ZonMW (Nederlandse organisatie voor gezondheidsonderzoek en zorginnovatie), Astmafonds en SBOH (werkgever van huisartsen in opleiding).UBL - phd migration 201