Over a 32-month period, 980 calls from asthmatic patients were received at the switchboard office of a prehospital emergency care unit. A total of 90 patients (9 percent) died before receiving any medical help, and 216 (22 percent) patients were taken to the hospital with an emergency care ambulance where none of them died. We made the assumption that, when an asthmatic patient calls an emergency care unit, the attack is severe and might be fatal. A prospective study was performed during a six-month period to prevent these asthma deaths: 259 calls from asthmatic patients were received. For each emergency call from asthmatic patients, paramedical help (delay: 5.1 +/- 0.3 minutes) and an emergency care ambulance (delay: 9.7 +/- 0.6 minutes) were immediately sent. Only four patients died during this period. Emergency calls from asthmatic patients must be considered as related to a severe attack that might be fatal. Fatal asthma is often related to a severe attack that evolves rapidly. Some asthmatic patients are able to assess the severity of asthma attacks, and prehospital emergency care schemes for asthmatic patients are actually able to prevent some asthma deaths.