Relevance. Incomplete payment or non-payment for medical care provided under the compulsory health insurance system affects the financial stability of a medical organization. According to the results of control and expert assessments conducted within the regional compulsory health insurance system, the leading defect in providing medical care to cancer patients is non-compliance with clinical guidelines. The aim was the self- and peer-assessment of the quality of oncological care and the identification of reasons for its inadequate provision, including non-compliance with clinical guidelines, based on the results of a sociological study. Methods. Using the method of qualimetric analysis, i.e., the quantitative determination of qualitative indicators, the self- and peer-assessment of the quality of oncological care by medical workers was assessed. A survey of 171 medical workers who provides care to cancer patients in the Arkhangelsk region was conducted. An original questionnaire was used, where the quality of medical care in the medical organization was assessed on a ten-point scale, and possible reasons for quality defects in medical care, identified based on the results of medical care quality expert assessments, were determined using a Likert scale. Results. A high level of self- and peer-assessment of the quality of oncological care was found (9 [9-10] points). Specialists consider the main reasons for inadequate medical care to be low wages, staff shortages, and excessive workload standards. At the same time, the majority of medical workers disagreed with the statements that the reasons for poor-quality care are a lack of knowledge among doctors, absence of equipment or medications, or poor organization of the institution's work. The high assessment of the quality of oncological care, found through our study by surveying the medical specialists does not coincide with the results of examinations conducted by medical care quality experts within the regional compulsory health insurance (CHI) system. Furthermore, the identification of low salary levels, the absence or shortage of specialists in a department/medical organization, and excessive workload standards for physicians as the leading causes of defects in oncological care characterizes a serious problem currently existing in Russian healthcare: a shortage of specialists, excessive workloads on existing staff, and, as a consequence, inadequate quality of medical care. Conclusion. The obtained results indicate that medical organizations possess the material, technical, and organizational capabilities to provide quality medical care to patients with malignant neoplasms, and that systemic reasons for its inadequate provision are related to the excessive workload on medical workers.