51Cr labelled red blood cells were transfused into nine patients during surgery, and the rate of chromium elutionin vivowas determined. Similar studies were performed on seven nonsurgical patients. Three of the surgical and two of the nonsurgical patients received liquid‐stored red blood cells, while six of the surgical and five of the nonsurgical patients received previously frozen agglomerated red blood cells. The rapid component of chromium elution was observed in both surgical and nonsurgical patients. Approximately 6.7 per cent of the chromium eluted rapidly from liquid‐preserved red blood cells, and about 9.9 per cent from previously frozen red blood cells. No further elution was detected in the red blood cells transfused during surgery, whereas further elution (the slow component of51Cr elution) was observed in nonsurgical patients. These data suggest that general anesthesia may have influenced the slow component of chromium elut