Laboratory experiments have been conducted to provide data for modelling the direction of sediment transport on a transverse sloping alluvial bed. Conditions with prevailing bed-load transport, and conditions in which a significant part of the bed material is transported as suspended-load are studied. The effect of a sloping bed on the direction of sediment transport is determined by conducting bed-levelling experiments. Comparison of the results with data of curved flume experiments and experience gained with numerical computation of the bed topography in natural rivers yields the conclusion that, at least for bed-load transport, a distinction should be made between laboratory conditions and natural rivers. For conditions with suspended sediment transport the transverse slope effect can not be modelled identical as for bed-load transport.