Introduction: Bronchiolitis is the most common acute infection of lower airways in infants and the lead cause of hospitalization between infants and young children. The most common pathogen that causes bronchiolitis is RSV. Specific prevention of RSV bronchiolitis exists only in form of passive immunoprophylaxis with palivizumab. Purpose: Purpose of this study was firstly to determine effectiveness and safety of palivizumab in prevention of RSV bronchiolitis according to valid indications and princip of prophylaxis, especialy in preterm infants. Patients and methods: This retrospective research included a group of finally 83 subjects who recieved palivizumab on Clinic of pediatrics, Clinical hospital center Rijeka from RSV season 2013/2014. to 2016/2017. Results: From RSV season 2013/2014. to 2016/2017., of total number of subjects who recieved immunoprophylaxis, RSV bronchiolitis had one girl from preterm group born at ≤3 weeks of gestation with congenital heart disease and pulmonary abnormalities. That girl is also only child in this research that was hospitalized because RSV bronchiolitis. The girl develops postbronchiolitic wheezing. There were no complications of clinical course and complications related with treatment. No child died because the RSV bronchiolitis. There were no side effects on any of applied doses. In the observed period from other respiratory infections get ill 35 male and 18 female subjects. Conclusion: This research has shown that palivizumab is currently a effective, safe and highly specific preparation for the prevention of RSV bronchiolitis in children according to valid indications. Such a conclusion refers only to this study, in order to be able to apply this results in general or at least for the population in Republic of Croatia, more detailed research is needed with a far larger sample.