Successful management of childhood asthma requires a thorough idea of the economic impact of asthma and its determinants, as policy makers and physicians inevitably influence the outcome. The aim of this study was to define the cost of childhood asthma in Turkey and its determinants. In April 2006, a multi-center, national study was performed where data regarding cost and control levels were collected. Asthmatic children (6-18 yr) with at least a 1-yr follow-up seen during a 1-month period with scheduled or unscheduled visits were included. The survey included a questionnaire-guided interview and retrospective evaluation of files. Cost and its determinants during the last year were analyzed. A total of 618 children from 12 asthma centers were surveyed. The total annual cost of childhood asthma was US$1597.4 +/- 236.2 and there was a significant variation in costs between study centers (p < 0.05). Frequent physician visits [odds ratio (95% confidence intervals)] [2.3 (1.6-3.4)], hospitalization [1.9 (1.1-3.3)], asthma severity [1.6 (1.1-2.8)], and school absenteeism due to asthma [1.5 (1.1-2.1)] were major predictors of total annual costs (p < 0.05 for each). The comparable cost of asthma among Turkish children with that reported in developed countries suggests that interventions to decrease the economic burden of pediatric asthma should focus on the cost-effectiveness of anti-allergic household measures and on improving the control levels of asthma.