BACKGROUND: Current treatment strategies for asthma and chronic obstructive pulmonary disease (COPD) emphasize the inhalation route, yet patients often misuse metered-dose inhalers (MDI). To address this problem, patient education by medical personnel has been recommended and a variety of alternate inhaler devices have been developed. METHODS: We surveyed medical personnel to assess their knowledge of and ability to use three widely used inhaler devices; MDI, MDI with a spacing chamber (Aerochamber, Trudell Medical, Canada), and a breath-actuated multidose dry powder inhaler (Turbuhaler, Astra Pharmacy, Inc., Conada). Thirty respiratory therapists (RT), 30 registered nurses (RN), and 30 medical house staff physicians (MD) were asked to demonstrate the use of each device using placebo inhalers and to answer 11 clinically relevant questions related to the use and maintenance of the tested devices. RESULTS: The RT's percent mean knowledge score (67 +/- 5 percent) was significantly higher than those achieved by either the RNs (39 +/- 7 percent) or the MDs (48 +/- 7 percent) (for all p < 0.0001). Similarly, percent mean demonstration scores for each device were significantly higher for RTs than either RN or MD groups; for MDI, 97 +/- 3 percent versus 82 +/- 13 percent and 69 +/- 24 percent, respectively (p < 0.0001); for the Aerochamber, 98 +/- 2 percent versus 78 +/- 20 percent and 57 +/- 31 percent (p < 0.0001); and for the Turbuhaler, 60 +/- 30 percent versus 12 +/- 23 percent and 21 +/- 30 percent (p < 0.0001). Knowledge of and practical skills with the devices were roughly proportional to the length of time the device had been in clinical use, Turbuhaler demonstration scores being lower than either MDI or Aerochamber scores (p = 0.05 and p = 0.09, respectively). More RTs (77 percent) had received formal instruction on the use of devices at school than either RNs (30 percent) or MDS (43 percent) (p < 0.05). CONCLUSION: We conclude that (1) many medical personnel responsible for monitoring and instructing patients in optimal inhaler use lack rudimentary skills with these devices, (2) nurses and physicians seldom receive formal training in the use of inhaling devices, and (3) newer inhaling devices designed to obviate problems of technique are at present less likely to be used well by medical personnel soon after their introduction.