Providing optimal care for a sudden, unexpected large amount of victims from a disaster or major incident is challenging. It requires an approach different from regular traumacare. The population as a whole, rather than the individual, should be the focus of management. This thesis focuses on medical preparedness, care and follow-up for victims of a disaster or major incident, and explores new opportunities for improvement of disaster relief using the Internet as a supportive tool. The Major Incident Hospital (MIH) , the Netherlands, is a unique facility that offers permanent, reserved facilities to provide acute , structured care for groups of patients after a disaster or major incident. Its contribution to preparedness is not limited to providing directly available resources without impact on regular care. It also offers expertise, infrastructure, organisation, support systems, training, research and systematic working methods adapted to provide the greatest good for the greatest amount of people in case of multiple simultaneous victims. Pre-arranged cooperation, between the military, a trauma center and the National Poison and Information Center add to its value. Group-wise treatment relief for incident victims showed to be advantageous for overview, logistics, registration, quarantine, emotional support and (pre)arrangements for family, media and security. The evaluation of all MIH deployments since its foundation in 1991 resulted in five concluding recommendations: 1) improvement of embedding of the MIH in regional and national procedures; 2) continued dedicated time and staff for training, research and development; 3) improvement of nuclear/biological/chemical decontamination facilities and preparedness; 4) implementation of standardized scoring systems; and 5) expansion of registration systems to the pre-hospital setting. Lack of overview of victims and difficulties in sharing information showed to be recurrent barriers to an effective response in major incidents and disasters. To overcome these problems, an online Victim Tracking and Tracing System (ViTTS) was developed. ViTTS offers a real-time overview of victims to all involved disaster relief partners. This is necessary to generate an adequate disaster response with optimized resource allocation (care- and cost-effective) and prevents unnecessary public distress. One of the deployments of the MIH was for the repatriated Dutch victims of the 2004 South Asian tsunami. Of the 500 Dutch that were in the affected area, 23 wounded victims were repatriated to the MIH on New Year’s Eve 2004-2005. Analysis of their wound cultures reinforces the neccesity of relief of repatriated patients in quarantine. Long term follow up of these patients shows that tsunami exposure with concomitant injury had considerable middle and long-term physical and emotional impact. For support to a broader group of tsunami victims an innovative online service was developed that offered information, an interactive forum, self-assessment in a survey and e-Consult. The website was availabale in 15 languages. Thirty percent of the Dutch tsunami survivors participated in the survey. The effect of the distaster on physical and emotional health was still considerable over 4 years. This requires a multidisciplinary approach of (after)care with long-term provisions. Growing Internet penetration worldwide and especially the rapid expansion of influence of online communities and social media offer new opportunities to deliver (self)care and perform research with the Internet as a platform.