Three neonates with gram-negative bacillary meningitis were treated with moxalactam after therapy with ampicillin plus aminoglycoside, trimethoprim-sulfamethoxazole, or chloramphenicol failed to sterilize the CSF. Clinical improvement and CSF sterility occurred after therapy with moxalactam was initiated. Moxalactam concentrations in CSF exceeded MICs of each organism. All three patients were cured of their infection. Moxalactam appears to be an effective antibiotic for the treatment of neonatal gram-negative bacillary meningitis.