This review describes cryptococcal meningoencephalitis, tuberculous meningitis, neurosyphilis, and toxoplasma encephalitis. Central nervous system infections are neurological emergencies associated with mortality or other outcomes. Therefore, early diagnosis and treatment are critical. Fungal or gondii infections are rare and affect compromised hosts who are HIV positive, have diabetes, or take immunosuppressive or anticancer drugs. Cryptococcal antigens in the serum and cerebrospinal fluid are useful for the diagnosis of cryptococcal meningoencephalitis. RPR and TPHA tests are useful for the diagnosis of neurosyphilis. Cryptococcal meningoencephalitis and tuberculous meningitis often develop into hydrocephalus, making VP shunt necessary. Antifungal drugs for cryptococcal meningitis are limited by the blood-brain barrier, making a full recovery difficult; in such situations, intraventricular antifungal treatment is required.