Morroniside is an important constituent of traditional Chinese medicines Fructus Corni with several bioactivities. An HPLC method for determination of morroniside in rat plasma and tissues was developed and the pharmacokinetic and tissue distribution characteristics of morroniside after intravenous and oral administrations were investigated. The bio-samples were prepared based on a simple protein precipitation and the separation of morroniside was achieved on a C(18) column with a mobile phase consisted of acetonitrile-methanol-0.1% formic acid (10:10:80, v/v) at a flow rate of 1.0 ml/min. Chromatograms were monitored at 239 nm and the temperature of column was kept at 25 degrees C. Pharmacokinetic study found that morroniside was absorbed and eliminated rapidly in rat and manifested linear dynamics at 10-40 mg/kg range and absolute bioavailability of morroniside was lower. Tissue distribution showed the highest level was observed in small intestine, then in kidney and stomach, but no morroniside was detected in brain, which indicated that small intestine, kidney and stomach were major distribution tissues of morroniside in rats, and morroniside had difficulty in crossing the blood-brain barrier. It was also found there was no long-term accumulation of morroniside in rat tissues.