The forced oscillation technique (FOT) allows the noninvasive assessment of the mechanical properties of the respiratory system. Given that the technique does not require patient cooperation, it is suitable for the routine evaluation of respiratory function in a variety of clinical applications. In this paper, the rationale and the most conventional equipment and data processing of the technique are described. A number of clinical applications of FOT are briefly reviewed. One common use of the technique is to assess respiratory function in patients with different pathologies and in epidemiology. One of the most referenced applications of FOT is in tests of airway responsiveness to inhaled agents (bronchoprovocation and bronchodilatation). Finally, two recent promising applications of FOT are described: monitoring respiratory resistance during invasive and noninvasive mechanical ventilation, and detection of upper airway obstruction during sleep.