Areflexia is part one of the clinical criteria required to make a diagnosis of Guillain-Barré syndrome (GBS). The diagnostic criteria were stringently developed to exclude non-GBS cases but there have been reports of patients with GBS following Campylobacter jejuni enteritis with normal and exaggerated deep tendon reflexes (DTRs). The aim of this study is to expand the existing diagnostic criteria to preserved DTRs. From the cohort of patients referred for anti-ganglioside antibody testing from hospitals throughout Japan, 48 GBS patients presented with preserved DTR at admission. Thirty-two patients had normal or exaggerated DTR throughout the course of illness whereas in 16 patients the DTR became absent or diminished during the course of the illness. IgG antibodies against GM1, GM1b, GD1a, or GalNAc-GD1a were frequently present in either group (84 vs. 94%), suggesting a close relationship between the two groups. We then investigated the clinical and laboratory findings of 213 GBS patients from three hospital cohorts. In 23 patients, eight presented with normal tendon reflexes throughout the clinical course of the illness. Twelve showed hyperreflexia, with at least one of the jerks experienced even at nadir, and exaggerated reflexes returning to normal at recovery. The other three had hyperreflexia throughout the disease course. Compared to 190 GBS patients with reduced or absent DTR, the 23 DTR-preserved patients more frequently presented with pure motor limb weakness (87 vs. 47%, p = 0.00026), could walk 5 m independently at the nadir (70 vs. 33%, p = 0.0012), more frequently had antibodies against GM1, GM1b, GD1a, or GalNAc-GD1a (74 vs. 47%, p = 0.014) and were more commonly diagnosed with acute motor axonal neuropathy (65 vs. 34%, p = 0.0075) than with acute inflammatory demyelinating polyneuropathy (13 vs. 43%, p = 0.0011). This study demonstrated that DTRs could be normal or hyperexcitable during the entire clinical course in approximately 10% of GBS patients. This possibility should be added in the diagnostic criteria for GBS to avoid delays in diagnosis and effective treatment to these patients.