Introduction:: The spectrum of various complications in critically ill GuillainBarre syndrome (GBS) and its effect on the prognosis is lacking in literature. This study aimed at enumerating the complications in such a cohort and their significance in the prognosis and mortality. Materials and Methods:: Retrospective case record analysis of all consecutive mechanically ventilated patients of GBS in neurology Intensive Care Unit (ICU) of a tertiary care institute for 10 years was done. Demographic, laboratory, and treatment details and outcome parameters were recorded. Results:: Among the 173 patients were 118 men and 55 women (2.1:1), aged 184 years. The average number of ICU complications per patient was 6.8 1.8 (median = 7, range = 112). The most common complication was tracheobronchitis (128). Other pulmonary complications were found in 36 patients. The next was metabolic hyponatremia (115) hypokalemia (67), hypocalcemia (13), stress hyperglycemia (10), hyperkalemia (8), hypernatremia (9). Sepsis (40), UTI (47), dysautonomia (27), hypoalbuminemia (76), anemia (75), seizures (8), paralytic ileus (5), bleeding (4), anoxic encephalopathy (3), organ failures (12), deep vein thrombosis (7), and drug rashes (1) were also noted. The complications, considered significant in causing death, Hughes scale 3 at discharge, prolonged mechanical ventilation (>21 days) and hospitalization (>36 days) were pneumonia, hyponatremia, hypokalemia, urinary infection, tracheobronchial infections, hypoalbuminemia, sepsis, anemia dysautonomia. Conclusion:: Active monitoring and appropriate and early intervention by the clinician will improve the quality of life of these patients and reduce the cost of prolonged mechanical ventilation and ICU stay.