Guillain-Barré syndrome (GBS) is an acute inflammatory polyradiculoneuropathy resulting in symmetrical muscle weakness and diminished reflexes. With lack of exact etiology, GBS usually develops as an antecedent infection. Other than the known risk of neurological complications after coronary artery surgery, which includes intracranial hemorrhage, embolic events and transient ischemic attack, we aimed to present a patient in whom GBS developed after an off-pump coronary artery bypass grafting (CABG). A 56 year-old-male presented muscle weakness and somnolence on the postoperative second day of CABG. There was no pathology other than suspicious plaque formations in cranial magnetic resonance imaging. Nerve conduction velocity study revealed prolonged distal latency, conduction velocity slowing and temporal dispersion of compound action potential which were all indicative of demyelination. Along with the clinical findings and high protein, glucose and cell number detected in cerebrospinal fluid, the diagnosis of GBS was made. The management of 0.4gr/kg/day intravenous immunoglobulin was initiated. During a period of 15-day intensive care unit follow-up, the symptoms started to improve at the 72th hour of intravenous immunoglobulin therapy. The patient was discharged in good clinical condition on postoperative 42 days. Despite the pathophysiological mechanism of GBS is still unknown, one should remain alert to the development of GBS after cardiac surgery because, the disease yields favorable prognosis once the diagnosis is made early, and the treatment, either plasmapheresis and/or IVIG, is initiated at once.