An empirical equation has been developed for rate of bed-load transport based on shear stresses, bed friction coefficient and particle properties. It has been calibrated by using laboratory and field data covering a limited range of sediment sizes (from fine non-cohesive silt up to a median size of 1.4 mm) and has been shown to apply to streams transporting sediment of median size up to 300 mm. Development of this equation followed the lead given by Bagnold (1980, 1986) and extended his work so that it can be applied to unsteady flows. It is in a form suitable for use in the study of estuaries and coasts. The parameters in the equation can be obtained in the field without great difficulty.