The objective of this study is to investigate the pharamacokinetic parameters of decursinol following oral administration in Sprague-Dawley rats. The plasma concentration of decursinol was determined by LC/MS with APCI positive mode. The m/z value of decursinol was observed at 247. Following oral administration of decursinol extract, the apparent clearance was $5.3{pm}2.7;ml/hr/rat$, the absorption half life was $2.5{pm}0.41;hr$, the elimination half life was $3.05{pm}1.57;hr$, and the apparent volume of distribution was $21{pm}12;ml/rat$. The LC/MS method was successfully applied to the pharmacokinetic study of decursinol.