Sixty-seven children who were hospitalized with a verified RSV infection were reexamined after 4 years at the age of 4 to 7 years. Twenty-four children had had no subsequent respiratory symptoms, 22 had wheezed 1-3 times and 21 had recurrent wheezing. A family history of atopy and a personal history of neonatal respiratory problems were more common in the group with recurrent wheezing, whereas paternal smoking was more frequent in the group with occasional wheezing. RSV infection in early infancy was more related to occasional wheezing than recurrent episodes. The spirometric data obtained from the force expirograms were normal, compared to the predicted normal values. In the children with recurrent wheezing, however, the values for PEF and the MEF25 were significantly lower in comparison with all the other children showing a mild obstruction.