This study was carried out to investigate the effects of lidocaine (Ld) on brain edema, local cerebral blood flow (ICBF), and neural function. Vasogenic brain edema was induced by exposing a cat's brain surface to air for 12 hours. The animals were divided into three groups as follows: the brains were not exposed to the air with Ld administration (unexposed group), the brains were exposed to the air without Ld (untreated group), and with Ld (Ld-treated group). In the unexposed group, Ld had no influence on either cerebral water content or the latency of N(1) component of somatosensory evoked response (SER). In the untreated group, the cerebral water content in the cortex, white matter and thalamus increased 12 hours after exposure. Local CBF decreased in these areas. The latency of N(1) component of SER was prolonged significantly 6 hours after air exposure. The amplitude of the direct cortical response (DCR) decreased significantly. In the Ld treated group, water content decreased and ICBF increased significantly in the cortex compared with untreated group. There was no significant prolongation of SER N(1) component latency even after 12 hours of air exposure. These beneficial effects of Ld on cerebral water content and ICBF of the cortex, and neuronal electrical activity were presumably due to the stabilizing effect on the cellular membrane and the improvement of microcirculation.