The purpose of this study was to assess the diaphragmatic excursion using the TM-mode ultrasonography with concomitant pneumotachography in eight normal and five asthmatic subjects before and after salbutamol. We report the results in normal and asthmatic patients of this procedure. Particular findings were demonstrated in asthma. Different significant correlations were found between sonographic and respiratory measurements. In view of the safety of this direct and real-time diaphragmatic investigation, we conclude that this new method could offer an effective and reliable procedure in the evaluation of patients with diaphragmatic dysfunction. However, our study was limited by the small number of patients included and definite conclusions should await further investigations.