Amisulpride, a selective antagonist of D2 and D3 dopamine receptors, is used as an antipsychotic drug. In this study, we reported a sensitive LC-MS/MS method for determining amisulpride concentrations in rat plasma, and a preclinical pharmacokinetic study in the rat. After a simple protein precipitation with acetonitrile containing methaqualone as an internal standard, the analytes were separated on a reversed-phase column with a mobile phase of 0.2 % aqueous formic acid and acetonitrile (3:7, v/v). The accuracy and precision of the assay were in accordance with FDA guidance for the validation of bioanalytical methods. This analytical method was used successfully to characterize the time course of the plasma concentration of amisulpride following oral administration of a single 10 mg/kg dose in rats.