Although asthma is common after wheezing in early childhood, the risk factors for and the prevention of later asthma are poorly understood. During the present follow-up study, a range of possible predictive factors for school-age asthma was evaluated. The study group consisted of 82 children hospitalized for wheezing at age < 2 years in 1992-93. The baseline data were collected on entry to the study. In 1999, the children were re-examined at the median age of 7.2 years. A structured questionnaire was applied to chart the symptoms suggestive of asthma, and the children were examined clinically. An exercise challenge test, as well as skin prick tests (SPT) to common inhalant allergens, was performed. Asthma was present in 33 (40%) children, 30 (91%) having continuous medication for asthma. The significant asthma-predictive factors, present on entry to the study, were blood eosinophilia (p = 0.0008), atopic dermatitis (p = 0.0089), elevated total serum immunoglobulin E (IgE) (p = 0.0452), and a history of earlier episodes of wheezing in infancy (p = 0.0468). SPT positivity in early childhood was also associated with school-age asthma (p = 0.002). In contrast, respiratory syncytial virus (RSV) identification during the index episode of wheezing played a minor role as a predictive factor for asthma. In conclusion, if hospitalization for wheezing occurs in infancy, more than every third child will suffer from asthma at early school age; the risk is significantly increased with recurrent wheezing in infancy and the development of allergic manifestations.