**Meningitis** – inflammation of the meninges. Serous meningitis is meningoencephalitis that differs from purulent meningitis in its clinical picture, epidemiology, treatment and prognosis. The spectrum of clinical forms of serous meningitis: hemorrhagic, serous vaccinal, sacroiliitis, septic, generalized (meningococcal sepsis), neurocutaneous (streptoderma, diphtheria). The most important factor in poor prognosis is late treatment. In the early period of the disease, when there are no inflammatory changes in the cerebrospinal fluid, the main method of differential diagnosis of meningitis is a spinal puncture. Treatment: antibacterial and antimycotic drugs, B vitamins, in the acute period - immunotherapy. Prevention of serous meningitis consists of preventive vaccinations against diseases that are the main cause of meningitis.