This prospective study of 169 adult patients hospitalized for severe acute asthma in four pneumology wards compared the incidence and costs of patients who were managed (group A) or not managed (group P) before hospitalization, according to the guidelines and international recommendations (11 criteria judged by experts). Ambulatory costs were calculated by questioning patients. Valuation of hospital costs was based DRGs weighted by length of stay. The incidence in group P patients was estimated at 70%; A patients were 14 years younger than those in group P and had less severe asthma. Their annual ambulatory care prior to hospitalization was less costly irrespective of age category or degree of severity (euro 685 vs. euro 1,145 in group A); their length of hospital stay was shorter (6.03 vs. 10.78 days), resulting in a lower cost of hospitalization (euro 2,820 vs. euro 4,843). In group P a specific education program based on increased understanding, compliance, self-management, and smoking cessation, particularly in young patients should lead to reductions in hospitalizations.