Mycobacterial opportunistic infections are a major cause of morbidity and mortality among patients living with HIV (PLHIV) worldwide. Nontuberculous mycobacterial (NTM) infection is one of the leading causes of opportunistic infection in patients with advanced acquired immunodeficiency syndrome i.e., with CD4 count less than 50/cu.mm. Mycobacterium avium complex (MAC) is among the most common opportunistic bacterial infections in those patients with advanced immunodeficiency apart from cryptococcal meningitis, progressive multifocal leukoencephalopathy, etc. Common presentations of mycobacterium avium complex are fever, lymphadenitis and respiratory disease. Immune reconstitution disease is also known to manifest with MAC infections in PLHIV on highly active antiretroviral therapy. Very few cases of central nervous system involvement due to NTM infection have been described. We are reporting a case of advanced acquired immunodeficiency who presented with brain abscess due to Mycobacterium avium intracellulare.