A simple biological signal generator capable of reproducing complex biopotential waveforms is described. It is constructed by a combination of digital and analog circuit components and can be used under different experimental conditions, such as in calibration of biomedical instrumentation systems, or simply as a function generator providing voltage outputs of various waveforms. The biopotential waveform to be generated is sampled at a high frequency and the samples are stored sequentially in a programmable read only memory (PROM). The samples are then fed in the same sequence to a digital-to-analog (D/A) converter and the resulting output is amplified and a DC offset is added. External controls are provided to adjust the DC offset, amplitude and repetition rate of the signal generated. The reproduced voltage signals are stable and superior in quality to those produced by conventional biological signal generators.