Introduction. The depolarization time of the compound action potential (CAP) represents a period between the onset and the peak of the CAP curve. The compound action potential is response of a peripheral nerve after the application of suitable stimulus. Objective. The aim was to examine the effects of high concentrations of lidocaine chloride on blocked sodium channels recovery. Method. This study was carried out at the Physiology Department, Faculty of Medicine, Motenegro, after National Ethic Committee approval was obtained. Isolated sciatic nerves (No20) from healthy adult frogs (R. Dalmatina) weighting 100-200 g were used in electrophysiological experiments. The animals were kept under ambient temperature (21-24 C) and natural light for 24 hours according with National Institute Health Guide for Care and Use of Laboratory Animals. Frogs were rapidly decapitated and then the sciatic nerves were dissected from the lumbar plexus to the level of the ankle and incubated in Ringer solution (2,0 mmol/l calcium solution) for two hours in order to achieve stable baseline and reproducible CAP. Afterward, control measurements of CAP depolarization time were taken. Then, the frog sciatic nerves were divided into two groups (10 nerves in each group), and were incubated for 15 minutes in the following solutions: Control group: Ringer solution; Experimental group: 100,0 mmol/l lidocaine solution. After that, nerves were washed and incubated in Ringer solution and the CAP depolarization time was measured at 30, 60, 120 and 180 minutes during recovery period. CAP was induced by stimulator with single electrical stimulus and recorded using digital oscilloscope. Data were collected and analysed using the statistical computer programme GrapPadPrism 5.0. Results. The depolarization time of all nerves in experimental group was blocked at 30 minute of recovery period. After 60 minutes the mean depolarization times were 308±35.5 μs and 431.1±82.5 μs for nerves in control and experimental group, respectively (p<0.01). The difference in the mean amplitude values between groups after 120 and 180 minutes of the recovery period, was not statistically significant. Conclusion. Knowing the fact that the CAP depolarization time shows the impact on sodium channel blockade, it may be concluded that lidocaine chloride in high concentrations reversibly blocks sodium channels, since the complete recovery of the depolarization time occurred 120 minutes after its application.