A program for action potential waveform analysis based on a PC compatible computer is described. Single or averaged action potentials are analyzed by obtaining its first derivative and using criteria which allow automatic measurement of several action potential components, including: depolarization rate, repolarization rate, amplitude, duration, resting membrane potential and afterhyperpolarization amplitude and slope. Data can be imported from pClampTM (Axon Instruments) and exported to other software such as ExcelTM, SigmaplotTM and MatLabTM for example. Key words: intracellular recording, ionic currents, intrinsic properties, data acquisition, waveform analysis, Helix aspersa.