OBJECTIVE To study the tissue distribution and excretion of bromotetrandrine (W198) in rats. METHODS The concentrations of W198 in biological samples were determined by an HPLC method with UV detection. RESULTS After a single i.v. dose of 20 mg x kg(-1) W198 in rats, the parent drug concentrations in tissues were higher than those in blood at the same time. Parent drug was mainly distributed in lung, kidney, heart and liver, the peak levels were attained at 0.25 h and decreasing at 2 h after dosing in most tissues. After a single iv dose of 20 mg x kg(-1) W198 in rats, the excretion of the parent drug in urine, feces and bile amounted to 0. 150%, 2.1% and 0.063% of the dose, respectively. CONCLUSIONS W198 was mostly distributed in lung. The parent drug excretion was less than 3% via urine, feces and bile.