Introduction: Group B streptococcus (GBS) is a leading cause of neonatal sepsis and meningitis. Although late-onset GBS meningitis is the most common form of the disease, it may happen earlier, like just a few hours after birth, known as the early-onset. GBS meningitis is associated with 30% mortality rate among infants. Of those who stay alive, 25% of them will develop adverse neurological conditions. Herein, we report a case of early-onset GBS meningitis in a female infant with brain abscess. Case Presentation: A 10-hour old female was admitted to the neonatal intensive care unit (of the University of Tehran) for poor feeding, irritability, lethargy, and seizure. Sepsis work-up and lumbar puncture were performed. The treatment was started with vancomycin, cefotaxime and phenobarbital. The GBS was isolated from both blood and CSF cultures. A cranial sonography revealed intraparenchymal hemorrhage. The infant’s hospital course was complicated by recurrent and intractable seizures. The brain MRI of the patient showed micro-abscess. After six weeks of medical therapy, the patient was discharged from the hospital in a good condition. Neurological evaluations of the patient, conducted two and five months after her birth, showed normal results. Conclusions: Neonates with GBS meningitis are prone to adverse neurological conditions, including brain abscess. Although GBS is a normal flora in the genitourinary tracts of 15 to 30% of women, routine screening and treatments of the GBS-positive women during their course of pregnancy could reduce such serious complications.