Scour at a downstream vertical gate of a dam is investigated using a fuzzy logic inference system. The application is presented for experimental data sets. A comparison is made between a regression formulation (RM) and a fuzzy logic approach. Some restrictive assumptions for RM are discussed. Here the Takagi-Sugeno (TS) approach is used with a constant function in the consequent part of the fuzzy rules. It is demonstrated that the TS model gives a lower error than the RM. Furthermore, scatter diagrams indicate that the TS approach has superiority over the RM.