ABSTRACT: The dike rings along the Rhine in the Netherlands have a level of protection of 1/1250 per year. The design water levels are estimated on the basis of one random variable: the river discharge. Van Vuren & Van Breen (2003) show the existence of large spatial and temporal variation in bed level position in the river Waal. In this paper the impact of river morphology on extreme flood level predictions is investigated. Therefore, the method to compute design water levels is extended with another random variable: the river morphology. The results show that the impact of river morphology on design water levels is limited. A random bed level prior to the design water level computations leads to small changes (order of 0.01- 0.06 m) in design water levels. The impact of seasonal variations in the river morphology and morphological changes during the flood wave can be neglected.