Accurate in situ determination of unsaturated soil hydraulic properties is often not feasible because of natural variability of most field soils, and because of instrumental limitations. Therefore the soil hydraulic properties are often measured in the laboratory, or derived by computer models using simple standard laboratory methods. This paper analyses problems in describing field hydraulic properties of a Ap horizon of a silty loam, basing on data from different laboratory methods: (i) A standard pressure plate apparatus and (ii) a constant-head permeameter were used to measure the static retention characteristics and the saturated hydraulic conductivity independently. (iii) An instantaneous profile method was applied to measure water retention and conductivity simultanously. Relatively new technics involving “undisturbed” soil samples instrumented with mini tensiometers and Time Domain Reflectometry (TDR) mini probes characterise the experiment. The models by Mualem and van Genuchten (MvG) were used to describe the soil hydraulic functions. The different laboratory results were then compared with the hydraulic field properties measured in instantaneous profile manner. The laboratory method allows a high spatial and temporal resolution; this facilitates an investigation of some of the assumptions made, when fitting the MvG models to hydraulic data. A reasonably good description of the hydraulic data was obtained when setting the residual water content, θ r, to 0 and the pore connectivity factor, l, to 0.5 because θ r and l were not sensitive. However, a poor fit resulted when the saturated water content, θ s, was equated to the porosity, and the saturated hydraulic conductivity, k s to its independently measured value. Values for θ s and k s derived from field measurements were somewhat higher than those obtained from laboratory samples. To demonstrate the influence of the different input data on a water balance, the cumulative drainage from an initially saturated soil column was simulated with different sets of hydraulic parameters estimated from field and laboratory data. Parameters derived from the laboratory results consistently yielded lower predictions of cumulative drainage compared to hydraulic parameters derived from field measurements. The differences were relatively small when an initial water content corresponding to 60 cm suction (field capacity) was used.