The epidemiology of brain abscess has changed with the increasing incidence of this infection in immunocompromised patients, particularly solid organ and bone marrow transplant recipients, and the decreasing incidence of brain abscess related to sinusitis and otitis. A number of new neuroimaging modalities, including single photon emission computed tomography, positron emission tomography, perfusion magnetic resonance imaging, and magnetic resonance spectroscopy, provide an initial noninvasive approach to diagnosis. The recommendations for the management of intracranial mass lesions in human immunodeficiency virus-infected individuals has changed as the incidence of toxoplasmic encephalitis has decreased with the use of trimethoprim-sulfamethoxazole prophylaxis. The epidemiology, pathogenesis, microbiology, clinical presentation, diagnosis, treatment and prognosis of brain abscess in the beginning of the 21st century are provided in this review.