We studied the utility of Vigileo monitor for grasping hemodynamics with a patient in a state of anaphylactic shock. The stroke volume variation (SVV) predicts fluid responsiveness of normal cases. In the anaphylactic shock resulting from biased blood distribution, not only blood pressure but also pulse pressure markedly decreased within a couple of minutes. SVV is calculated from the standard deviation of pulse pressure. Therefore the SVV could be overestimated during anaphylactic shock. A former version of Vigileo monitor underestimated the arterial pressure-based cardiac output (APCO) due to the underrating of a single stroke volume (SV) in a range of systemic vascular resistance (SVR) below 800 dyne x sec(-1) x cm(-5). The version 3.02 Vigileo monitor allowed for more accurate estimation of SV because its new algorithm was able to revise the apparently low SVR derived from the arterial waveform characteristics and hence provided more realistic SV and APCO values. It was thus concluded that this ver. 3.02 is useful for anesthetic management of the anaphylactic case.