Techniques for the economic valuation of hydrologic data have been developed in response to the need to allocate resources to activities which will provide the most value as well as to the trend over recent years for a general reduction in the extent of hydrologic data collection networks. It is perceived that quantitative estimates of the dollar value of such data would be the most effective way of adequately representing the case for future data collection. This paper reviews the developments which have occurred in data valuation techniques with particular, though not exclusive, emphasis on Australia. It is concluded that, although many advances have been made, the ultimate goal of a practical, generally applicable and systematic methodology has not yet been attained. However, the authors remain optimistic that this goal can be reached.