An introductory article outlines the intersection between foreign policy and global health interests, and a case study of Brazil's growing influence in international relations. This is the curtainraiser as this week PLoS Medicine launches a series on Global Health Diplomacy.

In the first article in the series, Harley Feldbaum and Joshua Michaud from the Johns Hopkins School of Advanced International Studies in Washington DC address how the public health community has "seized upon" the concept of health diplomacy to raise the profile of health in the practice of foreign policy, often uncritically. They observe that foreign policy priorities can often determine priority setting and funding for global health, reflected in recent times by the focus of certain governments on the threat of bioterrorism, risks of infectious disease like H1N1 influenza, and operations in Iraq and Afghanistan designed to "win hearts and minds."

Moreover, the authors argue, health interventions are sometimes used to further ulterior foreign policy objectives. For example, "countries are increasingly using health initiatives as a means to improve security, project power and influence, improve their international image, or support other traditional foreign policy objectives." For this reason, the authors conclude, public health advocates must engage with foreign policy interests with caution.

In the second article in the series, Kelley Lee from the London School of Hygiene & Tropical Medicine (LSHTM) and colleagues analyze the growing influence of Brazil in international relations and, in particular, its prominent role in negotiating the Framework Convention for Tobacco Control (FCTC). The authors report that Brazil has achieved this recognition by engaging in "soft power"— a diplomatic approach based on persuasion and collaboration, rather than economic influence or political domination. In the FCTC negotiations, Brazil was instrumental by serving as an exemplar for domestic tobacco control, engaging in "coalition politics," and providing leadership throughout the negotiation process. This use of soft power in global tobacco control follows on from Brazil's prominence in the access to medicines debate, focused on upholding the country's constitutional guarantee of access to anti-retr oviral drugs for people living with HIV/AIDS and negotiating firmly to ensure access within World Trade Organization guidelines.