Objective: To define the clinical and diagnostic characteristics of paraparetic Guillain-Barré syndrome (GBS) with weakness restricted to the legs, compared with the classic quadriparetic GBS. Methods: Prospectively collected data from a cohort of 490 patients with GBS, previously involved in therapeutic or clinical studies, were used to define the demography, clinical presentation, diagnostic investigations, and clinical course in patients with paraparesis during a 6-month follow-up. Results: Forty patients (8%) presented with a paraparesis without weakness of arms and hands. In 29 patients (73%), normal strength of upper extremities persisted during the follow-up period. Patients with paraparesis compared to patients with quadriparesis had a milder form of GBS, with less frequent cranial nerve involvement and less severe leg weakness, despite the fact that the majority of these patients were unable to walk unaided. Median time between onset of weakness and study entry was 6 days (interquartile range 4-11 days) for patients with paraparesis compared with = days (interquartile range 3-8 days) for patients with quadriparesis (p = 0.031). Fifty percent of patients with paraparesis presented with arm sensory deficits and 73% had reduced or absent arm reflexes. Nerve conduction studies demonstrated arm nerve involvement in 89%of these patients. At 6 months of follow-up, 98% of patients with paraparesis were able to walk unaided compared with 81% of the patients with quadriparesis (p = 0.008). There was no association between paraparesis and age, sex, or preceding infections. Conclusions: Paraparesis is an atypical clinical presentation or subform of GBS in which the diagnosis is usually supported by the presence of sensory deficits, reduced reflexes, or abnormal nerve conduction of the arms.