Thirty-four infants and children ranging in age from 2.5 to 180 months (mean, 40 months) were treated with parenteral moxalactam (150 mg/kg per day) for suspected or proved bacterial infections outside the central nervous system. Six patients infected with Haemophilus influenzae b, nine infected with Staphylococcus aureus, three infected with Streptococcus pneumoniae, one infected with Streptococcus pyogenes, one infected with Enterobacter aerogenes, one infected with Fusobacterium nucleotum, and one infected with Staphylococcus epidermidis, microaerophilic streptococcus, and Propionibacterium sp. were clinically and bacteriologically cured. One patient with polymicrobial pansinusitis did not respond to moxalactam. No patients developed meningitis. All of the isolates tested were inhibited by less than or equal to 5 micrograms of moxalactam per ml, except for one Staphylococcus epidermidis isolate which was resistant to greater than 20 micrograms/ml. Five patients had transient neutropenia which resolved after the drug was discontinued. The mean peak serum level was 106 micrograms/ml at 15 min after a 50-mg/kg dose. The mean elimination half-life was 91.2 min. These data indicate that this dosage of moxalactam is a safe and effective treatment for bacterial infections outside the central nervous system.