Background: The Guillain Barre syndrome (GBS) is the commonest cause of acute flaccid paralysis in much of the world, after the introduction of vaccine for poliomyelitis. Electrophysiological study may play an important role in further investigation of the pathogenesis and assessment of prognosis. This study was undertaken to see any changes in electrophysiological pattern at one month follow up and prognosis of patients with Guillain Barre syndrome. Methods: The study included 28 patients of Guillain Barre syndrome admitted between the period of July 2014 to June 2015 in the department of medicine and neurology, SP Medical College and AG Hospitals, Bikaner, India. The clinical diagnosis was based on criteria proposed by the national institute of neurological, and communicative disorders and stroke (NINCDS). Each patient was assessed both clinically (including disability score) and electrophysiologically at the time of presentation and at one month±seven days of follow up. Results: GBS was more common in early decades. Male to female ratio was 4.6:1. On electrophysiological study mixed pattern was most common (42.86%) followed by axonal (32.14%) and demyelinating (25%) patients. Mean disability score at the time of presentation was maximum for axonal pattern and the same group had minimum score at one month follow up indicating better recovery. Sequential electrophysiological changes were seen in this study. Axonal pattern had better recovery (77.78%) than demyelinating and mixed was worst with 16.67% mortality. Conclusions: Mixed pattern is predominant pattern on electrophysiological studies. Axonal pattern has better recovery. Secondary changes of electrophysiological finding in some of our cases suggest that primary demyelinating and mixed subtype could, be misinterpreted as primary axonal pathology without timely serial studies.