An epidemic of Enterobacter aerogenes sepsis occurred in seven patients within a four-day perlod in a large pediatric hospital. These patients had received solutions of D5W/0.2NS in 250 cc flexible plastic bags to which 2.5 cc (5meq) of KCi had been added in the hospital pharmacy. All seven patients developed fever and promptly defervesced with withdrawal of the suspect intravenous fluid and institution of appropriate antibiotics. In contrast to reports of epidemics in adults, no mortality occurred, phlebitis was rarely seen and the systemic signs of septicemia were less severe. E. aerogenes septicemia developed in 28% of the 25 children who received it least one unit of the suspect fluid. No cases occurred in children receiving other intravenous fluids. Three units of the suspect intravenous fluid being infused into patients and six of 178 used bags with KCI added were culture positive for E. aerogenes. Although the source of contamination could not be established, the hospital admixture program may have amplified the epidemic.