Abstract: AIM: To study the pharmacokinetics, absorption, distribution and excretion of oxiracetam(ORC) in rats and mice. METHODS: The drug concentration was determined by using an HPLC system with pre-treatment column for biological samples. RESULTS: The concentration-time curves in rat serum showed an open one-compartment model after ig doses of 100, 200 and 400 mg.kg-1. The half-life of absorption phase(T_1/2ka) and peak time (Tpeak)were found to be 0.11～0.36 h and 0.79～1.41 h, respectively. The elimination half-life(T_1/2ke) and mean residence time(MRT) were 3.18～4.05 h and 3.38～4.18 h, respectively. The mouse test with ig dose of 100 mg.kg^-1 showed that 80% of the administered dosage was eliminated from the gastro-intestinal tract 3 h after administration. One hour after dosing, ORC was widely distributed to various tissues and the tissue drug levels from high to low were heart, liver, kindey, brain, muscle, spleenm, intestine, stomach, testis, fat, lungs and ovary. ORC was excreted by about 80% of the administered dosage from urine within a 36 h period. Plasma protein binding ratio of ORC was found to be 10.5% at the concentration range of 50～200 μg.ml^-1. CONCLUSION: ORC is well absorbed when given orally and rapidly eliminated via the urine. The protein binding was found to be low.