Objective There are sufficient evidences to suggest that trans-resveratrol (T-Res) is effective at tumor inhibition in diverse cancer models, especially prevents skin cancer in mice.However, T-Res is rapidly cleared from the body with low bioavailability.The contradiction leads to hypothesize that not only T-Res but also the metabolites may be responsible for anticancer activity.The purpose of present study was to identify the metabolites of T-Res in urine, plasma, liver, lung and tumor tissue of melanoma mice and investigate the characteristics of the biotransformation of T-Res.Methods T-Res (100 mg·kg-1) was administrated to C57BL/6 mouse bearing transplanted melanoma (B16) tumor for 5 days.The mouse was fasted for 12 h before giving T-Res at the 5th day.Urine was collected and blood was obtained for 2 h after the last treatment with T-Res.Afterwards, mouse was killed and the liver, lung and tumor tissues were seperated.The urine and plasma samples were prepared by acidification and deproteinization.The samples of liver, lung and tumor tissue homogenate extracts were prepared by a series of procedures, respectively.The Thermo Finnigan high performance liquid chromatography with on line photodiode array detection and multi-stage mass spectrometric detection (LC-PDA-MSn) was used to analyze the samples.The T-Res and its metabolites was eluted with a mobile phase composed of methanol and 5 mM ammonium acetate in distilled water containing 2% 2-propanol at a flow rate of 0.2 mL·min-1 on a Agilent eclipse plus C18 column (2.1100 mm,3.5 lμm).In Comparing with the chromatograms of each blank sample and the authentic standards: T-Res, cis-resveratrol (Cis-Res),trans-resveratrol-3-O-glucuronide (T-Res-G) and trans-resveratrol-3-O-sulfate (T-Res-S), the metabolites in samples of urine, plasma,liver, lung and tumor tissues were identified, respectively.Results An analysis method using LC-PDA-MSn was established for identification of the metabolites in mouse after administration of T-Res.There were ten metabolites found in urine sample: T-Res-S (M1), T-Res-G (M2), trans-resveratrol disulfate (M3), trans-resveratrol sulfate-glucuronide (M4) and trans-resveratrol sulfate-glucuronide (M5, isomer of M4), trans-resveratroi diglucuronide (M6), dihydroresveratrol (M7), dihydroresveratrol monosulfate (M8), diresveratrol monoglueuronide (M9) and Cis-Res (M10); three metabolites found in the liver sample: T-Res-S (M1),T-Res-G (M2) and dihydroresveratrol monosulfate (M8); two metabolites found in the lung and tumor samples: T-Res-S (M1) and T-Res-G (M2).The parent compound T-Res was found in all the samples.Conclusion The biotransformation of T-Res was complex in mice.The metabolic pathways of T-Res included glucuronidation, sulfation, reduction of double bond and converting to cis-form, in mice.T-Res G and T-ResoS, as same as the parent T-Res, were widely distributed in tissues of melanoma tumor-bearing mice.