Day care exposes young children to more infections early in life and may thereby prevent the development of asthma and allergy. The objective of this study was to prospectively study the effects of day care on the development of asthma and allergic sensitisation during the first 8 years of life. Associations of day care and/or older siblings with asthma symptoms (wheezing, shortness of breath, and inhaled steroids taken in the last year), airway responsiveness, and allergic sensitisation were assessed in a longitudinal repeated-event analysis. Am J Respir Crit Care Med. ;180(6):491-8. Epub 2009 Jun 19.