The F wave latency has been used to diagnosis of proximal neuropathy such as radiculopathy. But it's diagnostic sensitivity is low due to inherent variability in clinical utilization. Therefore we studied the diagnostic significances of F wave persistency and latencies in lumbosacral radiculopathy patients who has been diagnosed as lumbosacral radiculopathy by clinical, radiological, and electrophysiological findings. 38 patients' common peroneal and posterior tibial nerve F waves were studied. Bilateral limbs were studied in normal 20 persons as control group. The persistency, minimal latency, and mean latency were obtained. The results showed that the persistency and minimal latency were not significant different between two groups and mean latency was delayed in patient group. We concluded that the persistency was not sensitive in the diagnosis of lumbosacral radiculopathy and the mean latency was more sensitive parameter than minimal latency in the diagnosis of radiculopathy.