Abstract: Enzyme addition in the hot water extraction of flavonoids from Ganoderma lucidum was investigated for improvements on the extraction efficiency and/or enhancement on the antioxidant activity of the extract. The single factor test and the response surface methodology were used to optimize the processing conditions. It was found that a maximized yield of flavonoids of 0.75 mg/g could be obtained with the use of a combination of cellulase, pectinase and neutral proteinase in the ratio of 2.07:0.86:2.11 for the extraction at pH 5.0 and 50^oC for 80 min. The resulting extract exhibited a high reducing power as well as free radical scavenging activities on DPPH and hydroxyl free radicals.