Abstract: In a monitoring system for the process-accompanying monitoring or detection of collision or overstress situations in machine tools (1), comprising a machine control (2) with one or more sensors (4) for detecting measured signals or measured signal curves, a monitoring means (6) in which a comparison of the measured signals or measured signal curves of at least one sensor (4) with stored monitoring thresholds is performed, and a bidirectional interface (8) between the monitoring means (6) and the machine control (2), it is provided that the monitoring means (6), apart from detecting collision or overstress situations in a machine tool (1) and transferring machine stop or machine reaction instructions to the machine control (2), also permanently stores the measured signals or measured signal curves of the sensors (4) as measured by the sensors (4) before, during and after a collision or overstress situation and the data and statuses of the machine control (2).