Thirty three sources of hygroscopic data for wheat are identified. Gravimetric methods predominate in the literature, followed by hygrometric methods which largely employ a dew Point technique for relative humidity determination. Hysteresis effects vary considerably in magnitude. The greatest difference between adsorption and desorption isotherms occurs in the 20–40% RH region. A table of equilibrium moisture contents interpolated from the data sets is presented for a Fixed set of temperatures and RH to enable comparison. The isotherm equations used to fit the data are also revewed. The Strohman-Yoerger, Modified-Oswin, Modified-Chung-Pfost, Chen-Clayton and Modified-Henderson equations are identified as the most suitable. Further investigation is needed to compare them.