Brown rices were abrasively milled to give 92% yield, and hydration and cooking rates of brown and milled rites were investigated. Diffusion coefficients of Japonica brown and milled races at 30℃ were smaller than those of J/Indica counterparts. The bran layer controlled the diffusion coefficients of brown rites at initial stage of hydration. The diffusion coefficients for Japonica and J/Indica milled rice. were 107∼114 and 74∼87 times greater than those for brown rices, respectively. The terminal points of cooking of brown and milled rites at 110℃ were similar among varieties. The cooking rate constants of milled rites were about 2-fold compared with those of brown rites.