The concept of dominant (stream) discharge in geomorphology has not been firmly defined. By defining it, on rational grounds, as that discharge at which, over a long period of time, most sediment has been transported, a definite value can be computed for a stream for which there are available duration-curve values of daily discharge and a sediment-rating curve. This has been done for 5 eastern and 4 western rivers. The dominant discharge, when expressed in terms of percentage duration, is remarkably consistent, and is found to be a lower discharge than has generally been considered as dominant.