A serial study of clinical and magnetic stimulation motor evoked potentials (MEP) was accomplished in 44 patients with the acute flaccid paralytic syndrome which occurred in Northern China in 1991. Control data were provided by 70 healthy subjects from the same area. The cases came from the same area where a so-called new "Chinese paralytic syndrome" had been reported. We found the clinical features of these 44 patients to be similar to those of classical Guillain-Barré. Prolongation of MEP latency at 2 sites or on 2 occasions was found in 36 patients of whom 26 showed obvious clinical and electrophysiological recovery within 4-8 weeks. Three cases showed reduced MEP amplitude with normal latency, but in 2 of them the amplitude recovered in 2-8 weeks. Only 2 cases had no response at all time. We think 41 patients (93.7%) had predominant nerve demyelination. The 3 other patients (6.8%) showed axonal degeneration which is within the range found in previous reports of classical Guillain-Barré. We conclude that the acute paralytic syndrome seen in the summer of 1991 in Northern China represents a classical Guillain-Barré syndrome with demyelination of motor and sensory fibers. There is no reason to consider any special nomenclature such as "Chinese paralytic syndrome" or "acute motor axonal neuropathy."