Background: The purpose of the present study was to investigate the influence of particular factors on the development of wheezing during hospital treatment of acute respiratory infections (ARI) and recurrent wheezing following discharge. Material and methods: Are followed 117 infants hospitalized because of ARI during 12-18 months after discharge. Infants underwent hospital treatment inside the time period from 2009 to 2011 years. The age of the infants at the time of hospitalization was in the range of 9 days – 11 months, 103 of them were not older than 6 months of age. 76 infants were boys and 41 were girls. These children were tested for the presence of RSV antigen in nasopharyngeal discharge using immunochromatographic assay described elsewhere. Nasopharyngeal smears were taken during the first 3 days of ARI. The role of different factors in the development of acute wheezing during hospital treatment as well as recurrent wheezing was tested by means of logistic regression. The frequency of episodes as function of particular factors was studied by means of multiple regression. After admission to the hospital children were tested for the presence of respiratory syncytial virus (RSV) antigen in nasopharyngeal discharge. Results: Pneumonia was diagnosed in 49 of them, bronchitis – in 58, bronchiolitis – in 2 infants. In 2 infants bronchitis was accompanied with otitis media. In 28 infants the pneumonia and in 45 infants bronchitis were accompanied with wheezing. Vast majority received hospital treatment up to 15 days and less. The factors that influence wheezing during ARI are the presence of RSV antigen in nasopharyngeal smears and age at the time of admission. The factors that independently influence the development of recurrent wheezing after discharge from the hospital are smoking in accommodation and average time interval (in months) during which one episode of ARI was observed as well as the age of the baby at the time of admission. Conclusions: RSV infection and older age of infants enhanced the development of wheezing during hospital treatment of ARI. Smoking in accommodation, frequent ARI episodes and older age at the time of admission enhanced recurrent wheezing after the discharge from the hospital. Allergic father and congenital heart malformation increased the frequency of recurrent wheezing episodes.