When it comes to coordination in the fight against contagious diseases, the WHO is the most important international actor. This article presents the International Health Regulations 2005; the WHO’s legal basis for coordinating the work to counter transboundary contagious diseases. The International Health Regulations 2005 vests in the WHO the power to ensure a coordinated response against these diseases, but experiences show that, as a general rule, states only half-heartedly follow WHO recommendations. The article identifies three important reasons why the WHO’s fight against transboundary contagious diseases has not been successful and it puts forward proposals for ways of remedying these weaknesses.