Instruction is critical in order to ensure correct technique with pressurized metered-dose inhalers (pMDIs) by patients. The aim of this study was to compare the effects over time of two educational interventions delivered in community pharmacy to pMDI users. In this randomized controlled parallel-group study, pMDI technique was assessed before and after written and verbal instruction, alone or with physical demonstration, at baseline and 4, 8, and 16 weeks. The study recruited 52 subjects with asthma or chronic obstructive pulmonary disease (COPD). Initially only 1/52 (6%) subject had correct pMDI technique (= checklist score 8/8), with mean baseline score 5 (SD 1) for both groups. Written and verbal information improved pMDI technique at 16 weeks (7 +/- 1, p < .05). Addition of physical demonstration resulted in significant improvement at weeks 4, 8, and 16 (7 +/- 1, 7 +/- 1, 7 +/- 1 respectively; p < .05 for each). Subjects receiving written and verbal information alone were less likely to return for follow-up than those receiving physical demonstration (8 weeks: 6/25 versus 19/27; p < .001). By the 8-week visit, 80% subjects in the physical demonstration group had correct technique prior to education, compared with 10% of subjects receiving written and verbal information alone (p < .05). There was some decline in inhaler technique by 16 weeks. The results demonstrate that adding a physical demonstration is more effective in improving pMDI technique than written and verbal instructions alone.