Dehydrodiisoeugenol (DDIE) is a lignan in the fruit of Myristica fragrans. It can be converted into several metabolites in in vitro and in vivo metabolism. In this study, the excretion of DDIE in urine and feces was investigated after intravenous (i.v.) and intragastric (i.g.) administration to rats. DDIE and its metabolites (M-1 and M-2) were measured using HPLC. The amount of DDIE and its metabolites excreted was higher in feces than in urine, suggesting that DDIE and its metabolites are eliminated primarily in the feces. Significant differences in the excretion levels of DDIE and its metabolites were seen between i.v. and i.g. administration. Greater amounts of DDIE and its metabolites were excreted following i.v. administration, suggesting that DDIE can exert a longer period of anti-inflammatory activity following i.g. administration. The accuracy, precision, recovery and stability of the analytical method in this study were satisfactory for the measurement of DDIE and its metabolites in rat urine and feces. Observations made in this study will contribute to understanding of the absorption, distribution, metabolism and excretion pathway of DDIE and will aid decision-making regarding the best mode of DDIE administration during treatment to maximize its anti-inflammatory effects. Copyright © 2011 John Wiley & Sons, Ltd.