We characterized the population of users of inhaled long-acting beta 2-agonists in the region of Friuli-Venezia Giulia, in Italy, and assessed changes in asthma treatment and control after initiating long-acting beta 2-agonists. All residents using formoterol or salmeterol between 1992 and 1996 were identified in the regional Health Databases. Utilization rates of asthma medications and hospitalization rates for asthma were computed for the year before and after the date of the first long-acting beta 2-agonist prescription. There were 3803 users of formoterol and 20,054 users of salmeterol. Overall, 65% of users were older than 54 years of age. All formoterol users and 86% of salmeterol users received their first prescription for the respective drug during the study period (new users). Among these new users, 50% had not received any asthma drug during the 4 months preceding the start of long-acting beta 2-agonist administration. Prior 1 yr utilization rates of asthma medications and hospitalization rates for asthma were greater among new users of long-acting beta 2-agonists than among new users of salbutamol and xanthines. In addition, formoterol new users had higher prior use of asthma drugs than new users of salmeterol. One year prior hospitalization rates for asthma were also higher among formoterol than salmeterol new users with rate ratios of 1.7 (95% CI 1.3-2.2) for patients younger than 45 and 1.5 (1.2-1.9) for older patients. Use of short-acting beta 2-agonists, oral steroids and xanthines significantly declined after starting formoterol, whereas the use of inhaled steroids increased after the start of either formoterol or salmeterol. Asthma hospitalizations decreased by 32% in patients under age 45, by 43% in older patients, during the year following the start of formoterol, and by 15% and 24%, respectively, after the start of salmeterol. We conclude that long-acting beta 2-agonists were mainly prescribed to middle-aged and elderly patients and that formoterol appeared to be preferentially prescribed to patients with more severe asthma than salmeterol. Changes in asthma treatment and reduction in hospitalization rates for asthma after starting formoterol and salmeterol are compatible with an improvement in the control of asthma.