Often river dunes are considered as regular bed patterns, with a mean dune height and a mean dune length. In reality however, river dunes are threedimensional and irregular features that cannot be fully described by their mean values. In fact, dune dimensions can be considered as stochastic variables. Their probability distribution can be characterized by a mean value and variance. The stochastic properties of dune dimensions are relevant for (see e.g. Van der Mark et al., 2005): • Shipping - highest crests • Pipelines & cables - deepest troughs • Modelling cross-strata sets - troughs, dune heights • Modelling vertical sorting - troughs • Modelling bed roughness - dune heights In the present research the stochastics of crest elevation, trough elevation and dune height are investigated by analysing three sets of flume experiments.