METHODS The performance of five oscillometric blood pressure monitors was tested by means of a simulator. The oscillometric signals of two healthy patients were replayed. These signals were superimposed by sinusoidal artefacts with increasing amplitude, to examine the influence of artefacts on the accuracy of the measurement. Each measurement was repeated 15 times. RESULTS The artefacts taken for this examination did affect the scattering of each single measurement rather than the mean value of the repeated measurements. The results did get worse with decreasing signal-to-artefact ratio. However, some monitors are able to handle these artefacts better than others. CONCLUSIONS It is obvious that the implemented software for the artefact treatment and the determination of blood pressure values differs from manufacturer to manufacturer. Some devices were able to separate relevant signals from artefacts better than others. The most critical point of the oscillometric method is the correct determination of the maximum amplitude of the oscillations, because it directly influences the accuracy of the displayed blood pressure values. The availability of a simulator to test automated sphygmomanometers has shown to be a good tool to examine the performance of these devices.