SummaryLymphocytic meningitis can be an expression of a wide variety of central nervous system involvement by diverse disease processes. Patients usually present with atypical symptoms. The cerebrospinal fluid formula is never diagnostic. The differential diagnosis is sometimes difficult and demands extensive investigations. Acute viral meningitis, which represents the largest group, has a good prognosis without specific therapy being required. Mycoplasma, chlamydia, rickettsia, leptospirosis, syphilis, Lyme disease, parasites, fungi or mycobacteria arc other infectious causes of lymphocytic meningitis. Because of their morbidity and mortality higher than that of viral infections, they require a specific therapy. Seldom bacterial infections cause a lymphocytic meningitis. In more chronic cases non-infectious diseases should be taken into account: sarcoidosis, lupus erythematosus, MCTD, Sjogren’s syndrome, Behcet’s disease, granulomatous angiitis, Mollarct meningitis, Vogt-Koyanagi-Harada syndrome and malignancies.