A 41-yr-old man developed anaphylactic or anaphylactoid shock 9 min after infusion of a modified fluid gelatin. The hemodynamic effects of shock from its onset were studied: fall in mean arterial pressure (MAP) and systemic vascular resistance index (SVRI), increase in cardiac index (CI) and stroke index (SI). When the infusion was stopped, a few min after the onset of shock, wedge pressure (WP) fell sharply and the patient experienced cardiac arrest without previous arrhythmia or other ECG anomaly, thus demonstrating the importance of maintaining the left ventricular filling pressure at a normal level in the course of anaphylactic shock.