gamma-Oryzanol has important applications in food, cosmetic and pharmaceutical industries. The objective of this investigation is to isolate gamma-oryzanol from residue obtained during the production of biodiesel from rice bran oil. Using rice bran oil as the feedstock, the content of gamma-oryzanol could be raised to 16% by a series of steps, which include degumming and dewaxing, acid-catalyzed esterification and vacuum distillation. More than 95% low-boiling point components, such as free fatty acid and fatty acid methyl ester (biodiesel), were obtained as the distillate. After applying solvent extraction to the residue, gamma-oryzanol content was increased from 16 to 35% with a recovery of 88%. Subsequent use of soxhlet extraction raised gamma-oryzanol content to 47% with a recovery of 97%. Finally, after applying silica gel column chromatography, gamma-oryzanol content was 83.79% with a recovery of 81.75%. The overall recovery was 69.82%. (C) 2007 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.