Despite improved medical management, meningeal tuberculosis mortality and other outcomes have changed slightly over time due to a delay in diagnosis and treatment. This study reports a rare case of tuberculous meningitis in an immunocompetent host, calling into question the commonly held belief that tuberculous meningitis is a disease of immunocompromised individuals. A 26-year-old male with no significant past medical history, tuberculosis, or indications of immunological compromise, was admitted to our hospital with a fever and altered mental status. He was drowsy, febrile (temperature of 38°C), had a heart rate of 110 beats per minute, and showed mild neck stiffness but no meningeal sign. A lumbar puncture on the third day of admission suggested tuberculous meningitis. He was treated for tuberculosis meningitis, and his condition slightly improved. However, the patient's condition suddenly worsened, and a repeat contrast computed tomography (CT) of the brain showed the development of ventriculomegaly and basilar enhancement. Insertion of an emergency ventriculoperitoneal shunt was performed; however, the patient died ten days after hospital admission. We report a fatal case of tuberculous meningitis in an immunocompetent patient. Healthcare practitioners must be trained to identify and diagnose tuberculous meningitis promptly. Early treatment of tuberculous meningitis based on clinical diagnosis and symptoms improves clinical outcomes.