In this chapter I will explore the landscape of international medical NGOs providing assistance in humanitarian settings. I will examine the varying mandates, motivations, tasks and accountability, and professional standards, and I will discuss the performance of these NGOs in most recent disasters. I will outline some critical steps needed to support the medical relief provided by agencies to ensure that it is up to date, credible and ethically acceptable. After all, there must be a balance between the intention to do good and the results of these actions. The content is based both on available literature and 25 years of experience of medical humanitarian work.