Respiratory syncytial virus (RSV) is the most common pathogenic agent responsible for respiratory viral infections in infants and young children. Therefore, the importance of research in the field has been driven by the need for effective preventive tools against RSV infection for children, especially those at high risk of severe RSV disease. Despite the on-going efforts to develop RSV vaccines, the passive immunization of children with a drug called palivizumab is the only reliable option for prophylactic use against RSV. The article presents data on the passive immunization carried out in Moscow in the 2021–2022 season, including the following: the patient routing, indications for immunization, and the organization of the immunization process. It also provides authors’ own data on the number of immunized preterm children born with low and extremely low birth weight which were collected during 11 immunization seasons. The article also reviews the structure of morbidity in this group of children. The authors emphasize a high prevalence of the comorbidity of respiratory and cardiovascular diseases. KEYWORDS: respiratory syncytial virus, preterm infants, very low body weight, very low birth weight (VLBW), extremely low birth weight (ELBW), bronchopulmonary dysplasia, immunoprophylaxis, palivizumab. FOR CITATION: Mironova A.K. The experience of passive immunization against respiratory syncytial viral infection: the twelfth season. Russian Medical Inquiry. 2022;6(11):659–666 (in Russ.). DOI: 10.32364/2587-6821-2022-6-11-659-666.