The concept of risk entails a broad discussion, ranging from a more general approach, seeking to contextualize it in the dynamic of societal change, to a more specific approach in the field of health, particularly in epidemiological studies on associations. The term "risk" has appeared with increasing frequency in medical journals in the last three decades, but the phenomenon is not exclusive to health and is permeated by the diversity of a notion that hides a conceptual gap. Given this diversity, the current paper begins with a literature review to systematize the discussion of risk. The result is organized in three sections: 1) an overview of the discussion on risk within the debate on societal change in the transition from modernity to a new phase of social organization; 2) a summary of various uses of the risk notion in health knowledge; and 3) the establishment of the epidemiological concept of risk and its link to clinical medicine.