Ethosuximide is an oral anticonvulsantic agent used in the first choice anti-absence seizure drug. The purpose of this study was to assess the pharmacokinetic profile of the ethosuximide in healthy Korean volunteers and to develop the efficient assay method of ethosuximide in human plasma. The pharmacokinetics of ethosuximide administered orally was evaluated after a dose of 500 mg. Ethosuximide was assayed from plasma by a specific HPLC method reading absorbance at 195 nm. AUC was 1222$pm$160 $mu extrm{g}$/$mell$$.$hr, $C_{max}$ 14.2l$pm$1.74 $mu extrm{g}$/$mell$, $T_{max}$ 1.06$pm$0.62 hr and half-life 77.83$pm$12.46 hr. The half-life in Korean was longer than, in Caucasian (53∼56 hr).).).