The brainstem abscess of a nine-year-old girl with tetralogy of Fallot was cured after six weeks of parenteral antibiotic therapy, without surgical intervention. Serial studies of brainstem auditory evoked potentials were undertaken until the patient was clinically normal. To the authors' knowledge, this is only the second medically cured case reported in the literature, and it is the first case studied with serial brainstem auditory evoked potentials. If the clinical status allows, medical treatment of a brainstem abscess with appropriate antibiotics could be tried before surgical intervention such as stereotactic aspiration for reducing the mass.