OBJECTIVE: To determine the concentration of sodium L-lactate in sodium lactate injection. METHODS: Lactic oxidase was immobilized at a hydrogen peroxide electrode and the enzyme electrode was used for the amperometric determination of sodium L-lactate in sodium lactate injection. Sodium D, L-lactate in injection was analyzed by that technique according to Chinese Pharmacopoeia. RESULTS: The quantity of sodium L-lactate was about 10% in total amount of sodium D, L-lactate in sodium lactate injection. CONCLUSION: Sodium L-lactate in sodium lactate injection could be determined specially, rapidly and inexpensively.