Over the past few decades, several naturalization methods have been developed for removing anthropogenic influences from streamflow time series, to the point that naturalized flows are often considered true natural flows in many studies. However, such trust in a particular naturalization method does not expose the assumptions underlying the method, nor does it quantifies the associated uncertainty. This review provides an overview of streamflow naturalization approaches. The terminology associated with naturalization is discussed, and a classification of naturalization methods according to their data requirements and main assumptions is proposed. A large set of studies developing or applying naturalization methods are reviewed, and the main challenges associated with the methods applied are assessed. To give a more concrete example, a focus is made on studies conducted in France over the last decade, which applied naturalization methods to estimate water extraction limits in rivers.