Tick-borne encephalitis (TBE) is a disease which may present as meningitis, encephalomeningitis and myeloencephalomeningitis. The course of the disease is usually mild although it may result in the patient's death in 1-4% of cases. Patients with myeloencephalomeningitis are the most endangered group, but also encephalomeningitis may have a fatal outcome. There are many risk factors which influence the severity of TBE, including patient's age, immunosuppression and concomitant diseases. We present four cases of patients who died because of TBE. The aim of the paper was to underline that in elderly patients or patients suffering from chronic diseases and additional infections, special attention should be paid to their treatment, including mechanical ventilation and steroid use.