Listeria monocytogenes is a gram-positive, intracellular bacterium of the family Corynobacteriaceae, it is rod-shaped, relatively anaerobic, and ubiquitous in the environment. Listeria monocytogenes is the bacterium that causes a disease called listeriosis that may take place under the form of mild, self-limiting infections or severe, life-threatening ones. In this article, we present the case of an 81-year-old patient with impaired consciousness, admitted to the Department of Nephrology with suspected urosepsis. The patient was treated with immunosuppressant (methotrexate) due to rheumatoid arthritis. He did not present meningeal symptoms, had a high fever, and his clinical status during admission was unclear. Listeria monocytogenes was identified in both blood and cerebrospinal fluid cultures. Despite intensive antibiotic therapy, the patient’s condition did not improve. Due to circulatory and respiratory failure, he required mechanical respiratory support and continues 33 days care in the Clinical Intensive Care Unit, and after extubation - further rehabilitation and treatment in the Nursing and Treatment Institution (ZOL). The presented case of the patient shows the diagnostic and therapeutic difficulties of Listeria monocytogenes infection in an elderly person treated with immunosuppressive therapy.