Background and objective: We recently developed and validated a screening questionnaire for determining which school-aged children may need further investigation to diagnose and manage asthma. In the present study we sought to extend this to pre-school aged children. Methods: Questions from the school-aged questionnaire and literature on pre-school asthma were used to inform a focus group of parents with pre-school-aged children with asthma to develop a screening questionnaire. Parents of children attending 6 randomly selected kindergartens in Trelew, Argentina (n = 639) were invited to respond to the questionnaire. A reliability test-retest was undertaken in 187 randomly selected parents who completed the same questionnaire twice within 2-5 weeks. Clinical assessment included a standardized history and physical examination, spirometry before and after a [beta]-agonist inhaler, and chest X-ray. Asthma was diagnosed by the pulmonologist. Results: Completed surveys were returned for 620 children, 607 of whom underwent clinical evaluation. The mean age was 4.21 years (range of 3.01-5.50) and included 82.5% white and 49.4% male children. Asthma was diagnosed in 103 (17.0%) children); 72 (69.9%) of these children did not have a previous diagnosis of asthma. The specificity, sensitivity, positive predictive value and negative predictive value of the questionnaire were 93.2%, 86.1%, 57.8% and 98.4%, respectively. Conclusions: We have demonstrated the utility of a screening questionnaire for identifying pre-school-aged children who may benefit from further assessment for asthma. (author abstract)