Measurement of interrupter resistance (Rint) requires only tidal breathing from the patient and therefore, can be used as a lung function test for preschool children. Analysis of recorded oscillations of the mouth pressure has been suggested to provide additional indices of change in airway mechanics. The aim of our study was to compare the relative sensitivities of several oscillation amplitude measures and Rint to detect changes during bronchoprovocation testing. Data from 44 preschool children who completed methacholine (Mch) challenge were analyzed. We calculated four different amplitude parameters that correlated strongly with each other and changed significantly after Mch. The most sensitive indices to describe the change in airway mechanics were the maximum instantaneous amplitude and the difference between the first pressure maximum and minimum. These findings suggest that oscillation amplitude analysis implemented in the software of commercial devices could have further applications.