We describe a case of a 47 years old male, with a history of 2 days of progressive, ascendant, symmetrical weakness in the lower extremities; a lumbar puncture was performed after the brain CT scan, as well as an electromyography, evidencing pure motor polyradiculopathy with axonal pattern, compatible with Guillain Barre syndrome. Afterwards, he received four plasmapheresis sessions, with clinical improvement from the second session. Due to his epidemiological background, Brucella set testing was done. Rose Bengal was positive, antibiotic treatment with rifampin and doxicicline was initiated, as well as rehabilitation. Three months later the patient recovered completely. The relevance of early treatment with plasmapheresis and the definition of the etiologic diagnosis determine that the prognosis of the Guillain Barre syndrome is favorable.