Viral encephalitis is one of the important directions of modern neurology. Practitioners have diagnostic difficulties that require differentiation from neoplastic process, acute cerebral vascular syndromes, toxic encephalopathy, psychosis. In this regard, own observations of difficulties in differentiating viral encephalitis from brain tumors are of clinical interest. Two cases with a diagnosis of viral encephalitis are presented. Neurological status, brain CT, EEG, Echo-EG, fundus examination, clinical laboratory tests, studies of cerebral spinal fluid , the data of objective history were analyzed. These observations reflect the different clinical manifestations of herpes encephalitis, the need for in-depth analysis of disease symptoms, their dynamics, results of paraclinical studies and mandatory differentiation, primarily with processes of vascular and neoplastic origin.