In this paper wave setup in river entrances is studied from both an analytical and experimental perspective. Field data from two shallow river entrances (h < 5m) show a surprising absence of wave setup, even during large wave conditions (Hrms > 3.5m). It will be shown that some of this anomaly can be explained by considering the possible mechanisms for wave height decay and their subsequent contributions to wave setup. Relatively simple analytical expressions are derived to show that wave decay from bottom friction, interaction with a porous bottom and diffraction give significantly less setup than that from wave breaking, and may be responsible for the "missing" setup.