Geologic and geomorphic data on 42 world deltas were compiled for a NASA-sponsored research project. Satellite images from 14 of these deltas (Danube, Ganges, Brahmaputra, Indus, Mahanadi, Mangoky, McKenzie, Mississippi, Niger, Nile, Shatt el Arab, Volga, Huang He [Yellow], Yukon, and Zambezi) were analyzed for delta plain wetland loss caused by natural causes and conversion of wetlands for agricultural and industrial use. These analyses indicated that a total of 15,845 km² of wetlands have been irreversibly lost during the past 14 years and the average rate of loss is 95 km²/y. If a similar trend is present in the other deltas, a total wetland loss in the delta plains of the 42 deltas would be on the order 364,000 km² over the past 15 to 20 years.