This work describes the complete automatisation of spirometry, the basic examination when assessing respiratory function. The movements of a water spirometer bell, transformed into electrical signals, are transmitted to a micro-computer, equipped with a digital analogue interface and then analysed. A few seconds after the performance of the examination the complete results are automatically edited in absolute values and as a percentage of predicted values (CECA). They are compared to previous calculations in the same spirometer, using the usual technique. The correlations obtained between the two series of results (145 examinations) show the reliability of the automated technique both for calculating volumes as for the maximal expired flows. In conclusion, while conserving the standard information in spirometry, the automatisation of this exam allows a considerable saving of time.