The objective of this study is to describe a series of cases of severe meningitis caused by human immunodeficiency virus type 1 (HIV-1) occurring during primary infection or after antiretroviral treatment interruption. In an observational cohort study, 13 patients with clinical diagnosis of meningitis or meningoencephalitis were reviewed. Ten cases occurred during primary HIV-1 infection and 3 after antiretroviral therapy (ART) withdrawal. Demographic parameters, clinical presentation and outcome, and laboratory and cerebrospinal fluid (CSF) parameters were recorded. The risk factor for HIV-1 infection acquisition was sexual transmission in all cases. The most frequent systemic symptoms were fever (12/13) and headeache (9/13). Among neurologic symptoms, focal signs appeared in seven patients (53.8%), confusion in six (46.2%), and agitation in five (38.5%). The median CD4 cell count was 434 cells/mm3. In all cases, CSF was a clear lymphocytaire fluid with normal glucose levels. Cranial computerized tomography was performed in seven patients, with a normal result in all of them; brain magnetic resonance in eight patients was normal in five cases and showing cortical atrophy, limbic encephalitis, and leptomeningeal enhancement in one patient each. The electroencephalographs (EEG) just showed diffuse dysfunction in three cases. ART was started in 11 patients. HIV RNA load at 12 months was <50 copies/ml in all treated patients. The 13 patients recovered without neurologic sequela. Meningitis or meningoencephalitis during primary HIV-1 infection or after ART cessation are unusual but sometimes a life-threatening manifestation. Although all patients tend to recover and the necessity of ART is not well established, some data suggest its potential benefit in these patients.