Guillain-Barré syndrome (GBS) generally presents sporadically. Epidemics of GBS are unusual. We reviewed the medical records of 26 patients hospitalized for GBS during the 2007 GBS epidemic in northeast China. The objective was to determine whether there were clinical and electrophysiological characteristics. All patients had drunk unboiled water, and the illness was preceded by diarrhea in 19 (73%) patients. Only 1 patient had a Campylobacter jejuni infection, whereas 14 (54%) patients exhibited features of acute motor axonal neuropathy (AMAN). The most common electrophysiological findings in early GBS included decreased compound muscle action potential (CMAP) amplitude (62%), abnormal F waves (73%), and abnormal H reflexes (62%). This epidemic of GBS appears to have been associated with consumption of contaminated water. The main subtype was AMAN, which was associated with a longer duration of illness and a worse prognosis. Electrodiagnostic evaluations are helpful for diagnosis in the primary stages of GBS.