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Gamma-aminobutyric acid (GABA) is one of the bioactive amino acids found in grains and its biosynthesis may be accelerated by applying a physical stress. Rice bran (RB) which is one of the common source of GABA was treated by an anaerobic incubation with nitrogen gas at 40? for 5 h after an adjustment of moisture content to 30% with an electrolyzed water. With the addition of electrolyzed water (pH 3), the anaerobic incubation increased the residual GABA content from 28.3 mg/100g RB to 176.1 mg/100g RB. A minor addition of glutamate (20mM) to RB further raised the GABA content to 669.4 mg/100 g RB, which was approximately 24 times higher than that in native RB. The conversion rate of glutamate to GABA was 88.5%. The GABA was extracted from the treated RB in different solvents (distilled water or aqueous alcohols: 50% or 70% ethanol) under different conditions (20 - 70? and 6 - 90 min). Extraction in 70% ethanol for 6 min at 20°C appeared most effective for GABA recovery, and the GABA content in the extract was 1013.5 mg/100 g RB. It was approximately 35.7 times higher than that in the native rice bran. The extract may be concentrated by vacuum evaporation to remove residual alcohol and to raise the GABA content. The rice bran GABA extract prepared by the anaerobic incubation may be used as a bioactive ingredient for various food products.