- The aim of this study was to examine a possible association between birth season (date of birth) and future development of asthma in children. A case-control study was designed to include asthmatic children aged 2–7 years, living in the city of Beer-Sheva, in southern Israel, registered in one pediatric center. Controls were healthy children matched for age and registered at the same clinic. Demographic data, past medical history, and asthma history and severity were collected using the computerized medical charts and asthma registry. A structured telephone questionnaire was used to complete the data. Children with a history of prematurity or chronic significant illness were excluded from the study. Sixty-six children and 69 controls were enrolled in the study. There were significantly more males in the asthmatic group compared to controls (P = 0.003). History of bronchiolitis or recurrent wheezing episodes in the first year, family history of asthma, and Middle-Eastern origin were significantly more common among asthmatic children than controls (P < 0.001). Asthmatic children were more likely to be born between March and June and least likely to be born between October and December, compared to controls (P < 0.05). Multivariate logistic regression analysis revealed three variables to be independent significant risk factors for development of asthma: birth season between March and June, acute bronchiolitis or recurrent wheezing episodes during first year of life, and male gender. Birth season during late winter and spring is associated with asthma during childhood. Pediatr Pulmonol. 2006; 41:1125–1128. © 2006 Wiley-Liss, Inc.