To describe Stenotrophomonas maltophilia infection in children, we reviewed the medical records of patients with isolates from nonrespiratory sites and identified 85 episodes, 51 (60%) of which represented true infection. Forty-two episodes (82.4%) were hospital acquired. Commonly associated with S. maltophilia infection were underlying illness (in 90.2% of cases), previous hospitalizations (in 78.7%), previous antibiotic exposure (in 78.4%), and the presence of a central venous catheter (in 76.5%). Polymicrobial isolates were obtained in 70.6% of episodes; Pseudomonas aeruginosa and Acinetobacter species were the most common coisolates. Bloodstream infection was the most frequent clinical syndrome (32 [63%] of 51 episodes). Fever or sepsis occurred in 22 (69%) and shock in 10 (31%) of 32 episodes. Infection at other sites was less severe. The most active antibiotics in vitro were trimethoprim-sulfamethoxazole and ticarcillin-clavulanate. The overall and attributable mortality rates were 12.5% and 6.3%, respectively. S. maltophilia appears to be an important cause of nosocomially acquired bacteremia in children. The significance in children of isolation from other sites is less clear.