Miller-Fisher Syndrome (MFS) is considered to be a variant of Guillain-Barree Syndrome (GBS). The typical clinical features of MFS include external ophthalmoplegia, ataxia and areflexia. Anti-GQ1b antibody is an important biomarker for the diagnosis of MFS, not just for typical MFS but also for ‘lessextensive forms’ and ‘massive-extensive forms’ of MFS. ‘Anti-GQ1b antibody syndrome’ was used to describe continuous spectrum with positive anti-GQ1b antibody. Here we report a rare case of anti- GQ1b antibody positive MFS associated with cognitive impairment. Our case suggests that cognitive impairment is one of the clinical symptoms of anti-GQ1b antibody syndrome which may be overlooked in clinical practice.