This discussion paper interrogates recent estimates of HIV prevalence in PNG and explores the relevance of international conceptualisations of HIV epidemics to the situation in PNG. It contributes to the quest to ‘Know your epidemic, know your response’, in particular in PNG contexts . The global endeavour to better ‘know your epidemic, know your response’ constitutes recognition that there are many diverse HIV epidemics and many different ways of responding to them. No single account captures their diversity. No single response keeps them at bay. Our understanding of an epidemic needs to guide us towards effective responses. So far this has not happened to any great extent. In 2007 globally some 2.5 million people became newly infected .