According to the definition (body mass index>97 degrees percentile), overweight and obesity concern 15% of French children. The parallel trends in the increase in asthma and obesity may indicate a potential link between these two conditions. The purpose of this study was to review the epidemiological data indicating a relationship between asthma and obesity, to evaluate the consequences of obesity on asthma and to assess the mechanisms of this association. We conclude with the implications for treatment strategies.