A 10% soybean oil emulsion (Intralipid) has been demonstrated to be an effective means of delivering an adequate caloric intake via a peripheral vein. This emulsion has generally been considered safe and free of significant complications. This is a report of a child who initially thrived on this intravenously administered fat emulsion, then suddenly developed a lifethreatening intolerance to the infusion, which appeared to be the "fat overload syndrome." This syndrome, seen frequently with earlier fat emulsions, has not been reported previously as a complication of the 10% soybean oil emulsion.