In this work, ultrasound-assisted aqueous extraction of oil rice bran was investigated. Key factors affecting ultrasound-assisted aqueous extraction of rice bran oil were identified. The results showed that high pH (pH 12) and high temperature (45 C), agita- tion speed of 800 rpm and agitation time of 15 min was preferred for aqueous extraction. Due to the ultrasonic processing, the reac- tion process was strengthened rapidly in a certain period of time. But while the time was too long, cavitation effect would weaken or even disappear at this time, so the rate of oil extraction could reduce. The optimum extraction time of 70 min was selected for ultrasound-assisted extraction of oil from rice bran. Also, the results showed that the temperature of the solution at ultrasound treat- ment is increased the amount of oil extraction decreased. At ultrasound-assisted aqueous extraction, the yield of rice bran oil was close to the yield of oil extracted by hexane Soxhlet extraction. The ultrasound pretreatment has been shown to be effective for aqueous extracting rice bran oil. Both extraction methods (aqueous and Soxhlet) gives higher percentage of oil from par boiled rice bran compared with raw rice bran. This may be due to the fact that par- boiling releases the oil in the grain and results in outward migration of the oil. With regard to quality, the oil extracted by aqueous pro- cess had a lower content of free fatty acid and lower color imparting components than the hexane-extracted oil.