A randomized double-blind, triple crossover study was conducted on 20 asthmatic patients (7 males and 13 females; age 40.9 +/- 14.2 Caucasians, 11 blacks, and 1 oriental. Criteria for admission included FEV1 < or = 80% of predicted when inhaled beta-agonists were witheld for at least 6 hrs and oral beta-agonists for 12 hr, in addition to at least 15% increase in FEV1, 15 min after treatment with albuterol with spacer delivery. Each of the study patients were tested on each of 3 separate days (within the same week) at baseline, 15, 30, 60, 120, 180, 240, 300, and 360 min post treatment. On each day albuterol was delivered by one of the 3 delivery devices and the other two methods delivered placebo. Albuterol was administered at the maximum recommended dosages of two puffs for MDI. Two puffs for MDI with spacer, and two capsules for Rotahaler. Spirometry, blood pressure and heart rate were measured at each testing interval. The mean percentage in FEV1 was higher in Rotahaler group compared to MDI with spacer (p < 0.001) and no significant difference in FEV1 was found between Rotahaler and MDI alone (p = 0.31). No significant changes in heart rate or blood pressure were associated with albuterol delivery by any of the three methods. Albuterol inhaled as a microfine powder was more effective than the same drug delivered as an aerosol by either MDI or MDI with spacer.