Incubation of quercetin with Cunninghamella elegans ATCC 9245 yielded three metabolites, including quercetin 3-O-beta-D-glucopyranoside, kaempferol 3-O-beta-D-glucopyranoside and isorhamnetin 3-O-beta-D-glucopyranoside. Glucosylation, O-methylation and dehydroxylation were involved in the process, among which dehydroxylation has never been found in Cunninghamella. Quercetin was completely metabolized in 72 h. (c) 2011, The Society for Biotechnology, Japan. All rights reserved.