A new field experimental method of determining unsaturated soil hydraulic proper ties is proposed. In this method these properties are assumed to be represented by van Genuchten's closed-form expressions. Unknown parameters of this model are identified by Genetic algorithms (GA) incorporating finite element analysis of transient axisymmetric seepage flow. GA are search algorithms based on the mechanics of natural selection and natural genetics. They have become a popular global optimization method. A ponded single-ring infiltrometer technique, such as the Guelph Pressure Infiltrometer is performed. Simultaneously the measured change of soil water content with time and cumulative inflow data are used to identify unsaturated soil hydraulic function parameters. The advantage of the proposed method are that it allows estimation of the unsaturated soil hydraulic parameters and diminishes experimental time. The utility of our proposed method is demonstrated by using experimental data for Japanese dune sand.