After ig and iv 3H-berberine in rabbits, the plasma radioactivity-time cure was found to be 2-compartment open model. The pharma-cokinetic parameters were: T1/2B 35 .3?1 .3h ( ig ) and 35.8 ? 2.0h (iv), Vd 20 ?3 L/kg(ig) & 22.1?1.7 L/kg ( iv ) . 3H-berberine was rapidly absorbed & taken up by various organs . The highest radioactivity was found in lung, followed by liver, spleen & heart. The rate of binding with plasma protein was 38 ? 3 % . In 6 d cumulative excretion of radioactivity was 73% of total dose in urine & 10.9% in fe-ces . 3H-berberine was excreted mainly in unchanged form, as measured by TLC & liquid scintillation counting in urine & bile.