The HIV pandemic continues to evolve, in both magnitude and diversity. In this paper, we briefly review the global epidemiology of HIV/AIDS, reflecting on the differences by region, and the challenges posed by the evolving epidemics in terms of prevention and surveillance. Despite the reduction in numbers of new AIDS cases in the US and Western Europe due to advances in treatment, a constant number of new HIV infections persists every year, with evidence that in some settings high-risk behaviour has increased, indicating failure in primary prevention. However, the vast majority of new infections still occur in developing countries. The two giants, India and China, are set to determine Asia's ultimate contribution to the pandemic, but currently it is Africa that remains in the eye of the storm, with rapidly increasing epidemics in many countries in the south and east of the continent impacting on all levels of society.