The authors are developing a computer-based method for identifying individual action potentials in multiunit peripheral nerve recordings. Threshold-level, sinusoidal stimuli are used to elicit phase-locked activity from single units. These action potentials are digitized, and a template is constructed using various waveform parameters. Once templates have been generated for all the units, the program is used in a sorting mode in which action potentials are detected and digitized, and parameter values are measured and compared to the template values. The output of the program is an indication of the instantaneous firing rate of each identified unit as a function of time. In principle, the sorting could be done online in real time.