detection and immediate installation of appropriate therapy. Given the low sensitivity of sputum smear and culture of bacillus tuberculosis, other tools should be explored in the differential diagnosis of tuberculous meningitis such as adenosine deaminase (ADA) isoenzymes. Objectives: To determine ADA isoenzymes activity in cerebrospinal fluid (CSF) of patients with tuberculous meningitis. Design: Descriptive study, with non-probability sampling. Institution: Biochemistry and Nutrition Research Center, Universidad Nacional Mayor de San Marcos, Lima, Peru. Biological materials: Samples of CSF from patients with clinical symptoms of tuberculous meningitis. Interventions: Samples of CSF with ADA activity above 9 U / L were stored at -40°C until vertical electrophoresis was run. Mann - Whitney statistical analysis was used with 0.1 significance level to compare meningeal tuberculosis ADA va...