Background: Data on trends in the prevalence of childhood asthma in France are scarce. Methods: National school-based health surveys are conducted on randomly selected samples of students, alternating between kindergarten, fifth grade (CM2), and ninth grade. The cumulative prevalence of asthma and the prevalence of asthma symptoms over the past 12 months were estimated using data from surveys conducted in CM2 in 2007–2008 and in ninth grade in 2008–2009. These were compared to the prevalence rates estimated in previous surveys (CM2 in 2004–2005 and ninth grade in 2003–2004). Results: the cumulative prevalence of asthma was 14% in CM2 and 16% in ninth grade. At each grade level, the prevalence of wheezing in the past year was 10%. Compared to previous surveys, there was an increase in the cumulative prevalence of asthma and in the prevalence of certain asthma symptoms over the past year. However, the proportion of students with asthma who had frequent or severe symptoms in the past year remained stable regardless of grade level. Conclusion: The observed trends will need to be confirmed by data from future surveys. The data available to date do not show any improvement in asthma control among children. (R.A.)