Guillain-Barré syndrome (GBS) is an acute inflammatory polyneuropathy that may lead to quadriparesis, ventilatory failure, and autonomic dysfunction. While significant mortality due to ventilatory failure has been associated with this syndrome, this complication can now be readily managed. However, an estimated mortality of 5% to 20% remains attributable to medical complications (pulmonary embolus, sepsis) and to acute cardiovascular collapse due to autonomic failure. In this report, detailed sequential changes in hemodynamic parameters, as measured by Swan-Ganz catheter, associated with severe autonomic cardiovascular instability in a patient with GBS are described. Knowledge of changes in these hemodynamic parameters led to optimal therapy. Long-term Swan-Ganz monitoring in an intensive care setting may dramatically benefit the critically ill patient with GBS and cardiovascular autonomic dysfunction, and may help to eliminate the residual morbidity and mortality associated with this disease.