<p>Proper inhalation technique is crucial for the effectiveness of inhalation treatment in obstructive lung diseases. However, many patients do not use their inhaler properly. There is a lack of clear guidance on how to effectively train inhalation technique. One of the tools that can be helpful in assessing the inhalation technique and at the same time allows to train correct inhalation technique is the Vitalograph AIM. The aim of the study was to assess the effectiveness of inhalation technique training using Vitalograph AIM in patients with asthma or COPD. This was a prospective, single-centre, interventional, non-randomized study. Patients with asthma and COPD who were treated with any inhaler on a daily basis were enrolled. Inhalation technique was assessed using Vitalograph AIM and then all patients, who did not use their inhaler correctly were trained using this tool. The improvement in inhalation technique and duration of training were measured. 121 patients were enrolled in the study (82 with asthma and 39 with COPD). Only 42 patients (34.7%) used a single type of inhaler while the remaining patients used ≥ 2 inhalers. Ninety-one patients used MDI, and 79 patients used DPI. At baseline, correct inhalation technique was found in only 6/91 (6.6%) patients using MDI and 34/79 patients (43%) using DPI. Training with Vitalograph AIM resulted in improvement and correct inhalation technique in 57/85 patients using MDI (67.1%) (<i>P</i> &lt; 0.001) and 18/45 (40%) using DPI (<i>P</i> = 0.016). After training among patients treated with MDI, correct inhalation technique was found in 46/91 (50.6%) patients using MDI and 50/79 patients (63.3%) using DPI. Training with Vitalograph AIM may be associated with improvement in inhalation technique, especially in patients using MDI.</p><p><i>Trial registration</i>: This study was registered at ClinicalTrials.gov (NCT04349735) on 16-12-19.</p>