Initiatives like GINA (Global Initiative for Asthma) permitted to better define epidemiological and physiopathological data in asthma, and to classify asthma severity based on clinical criteria. However, a small proportion of asthmatic patients remains symptomatic even with a well adjusted treatment. This refractory asthma phenotype is probably associated with heightened neutrophilic airway inflammatory response, tissue injury and remodelling. Recent studies investigated new therapeutic aspects related to causative (allergy for instance) or inflammatory (TNF-alpha) aspects of refractory asthma. Even though these new biological treatments are very expensive, they could be cost effective in case of demonstrated efficacy since patients with severe refractory asthma account for a substantial proportion of the health costs.