Using whole-cell configuration of patch clamp technique we found that mexilet-ine (Mex) reversibly inhibited the sodium cur-rent in a voltage- and use-dependentmanner in cultured dorsal root ganglion (DRG) neurons.The threshold concentration of Mex was 5μmol· L-1. The inhibitory action heightened with increasing concentrations of Mex. Com-plete inhibition was achieved at 150 μmol·L-1and the 50 ％ inhibition concentration was 31μmol·L-1. It is suggested that the inhibition of Mex on sodium current in neurons may be one of the mechanisms of its anti-ischemic and anti-anoxic effects on the neuron.