PURPOSE: Penicillin or ampicillin with aminoglycoside is the drug of choice for Group B streptococcal(GBS) meningitis in neonates. Some GBS meningitis, however, does not respond well to the treatment. The purpose of this study was to evaluate the efficacy of early penicillin treatment for the GBS meningitis in neonates. METHODS: Nineteen cases of GBS meningitis which was proven by CSF culture(13 cases) or latex agglutination test(17 cases) from 1999 to 2007 were retrospectively reviewed. In all cases 3rd-generation cephalosporin was initially given with ampicillin or aminoglycoside. Penicillin was added on the initial regimen according to the CSF results. Seven cases with penicillin given within 3 days of admission(early group) were clinically compared to the other cases(late or non-penicillin group). RESULTS: Fever continued for 3 to 23 days in the early penicillin group, for 2 to 23 days in the late penicillin group, and persisted in the non-penicillin group. Time needed for negative conversion of CSF bactigen or culture, however, revealed no statistical differences in those 3 groups. Vancomycin was effective in cases with poor responses to other antibiotics. CONCLUSION: Early penicillin treatment in combination with other antibiotics seemed to shorten the fever duration in the neonatal GBS meningitis.