The ParaGraph is a new device for monitoring neuromuscular function using a piezoelectric motion sensor. In 20 patients, monitoring of neuromuscular block produced by cisatracurium 0.1 mg kg-1 was compared using the ParaGraph and a Relaxometer 2 mechanomyograph. The ParaGraph was quick to set up, and easy to operate and interpret. There were no significant differences in the time to 100% depression of T1/T0, time to 25% recovery of T1/T0 or time to recovery of T1/T0 from 25% to 75%, measured by the two monitors. When the difference between the two monitors was plotted against the average of the two measurements, the limits of agreement for T1/T0 (-42.95, +53.98%) and the train-of-four ratio, T4/T1 (-0.28, +0.21) were too wide to allow the values given by the two monitors for individual patients to be used interchangeably.