The incidence of primary brain tumors is increasing worldwide. When assessing the treatment delivered to patients with brain gliomas, their quality of life (QOL) is an essential criterion for consideration. It is necessary to search for and specify the factors, which determine the QOL changes in patients with brain tumors. The QOL indicators for patients with brain gliomas were assessed in terms of the following factors: clinical (presence of epileptic seizures, seizures type and frequency, antiepileptic drug treatment, presence of speech disorders and pareses), demographic (sex), age of diagnosis, social (level of education, employment, marital status), molecular-genetic (presence of IDH1/2 mutation, 1p/19q codeletion), and morphological (malignancy degree, tumor histological characteristics). The QOL of 48 patients with diffuse brain gliomas was tested according to the objectives of the study. The QOLIE-31 questionnaire (version 1.0) indicates that diffuse glioma patients with epilepsy have statistically significant decrease in such QOL spheres as seizures worry (p<0.0001), cognitive functioning (p=0.0043), antiepileptic drug effect (p=0.0002), social functioning (p=0.0029), as well as in the total score (p=0.0053). In addition, such factors as age, gender, tumor malignancy degree, and its histological type have a statistically significant effect on the QOL of patients with diffuse brain gliomas before surgery. Thus, the treatment of patients with diffuse brain gliomas requires a thorough study and a multidisciplinary approach, including such specialists as a neurologist, oncologist, chemotherapist, radiologist, neuropsychologist, and psychiatrist, in addition to a neurosurgeon.