The TOF-GUARD™ is a new device for monitoring the neuromuscular function using acceleration measurement. It is quick and easy to apply and does not require a rigid support for the arm. Forty-one patients were studied to assess the monitoring of vecuronium neuromuscular block (NMB) using accelerography by the TOF-GUARD™ compared with electromyography by the Relaxograph®. Although the mean first twitch (T1%) and mean train-of-four (TOF) ratios measured by the TOF-GUARD™ corresponded to a certain extent with the Relaxograph®, the wide variations of the values for individual patients measured by the TOF-GUARD™ compared with the Relaxograph® and the differences in clinical duration and recovery index between the two monitors do not allow the values of the two monitors to be used interchangeably. The levels at intubation as well as at full recovery of the patients can be assessed equally by the two monitors. Thus, the TOF-GUARD™ is a reliable clinical monitor in daily anaesthesia practice.