Poverty, social disadvantage and ill health are interrelated. Around the world, poorer and more deprived people tend to have poorer health outcomes than the better off and more advantaged people. This health disparity is commonly referred to as “health inequality.” While health inequality is well studied in long-term developed Western populations, research on this subject is relatively new in the more recently developed populations. We will review the evidence of health inequalities across various socio-economic groups in Hong Kong, one of the first Chinese populations in the world to have been experiencing a very rapid economic transition from pre-industrial to post-industrial living conditions over the past few decades. In this article, we will first review the various important dimensions related to health inequality for a more comprehensive understanding of the concept itself. Then, we will describe the history of the population and the general poverty and social deprivation situations in Hong Kong, and move on to summarizing the evidence for the association of social disadvantage with health inequality in Hong Kong. Last, we will identify the gaps in the research literature and propose studies to be conducted in the future for a better understanding of health inequality.