Two systems based on microcomputers with analog-to-digital (A/D) converters were developed to measure sympathetic nerve activity. The first utilized a relatively inexpensive computer and A/D converter and an analog technique to count nerve traffic "spikes" above a reference voltage. The second system, which required a more expensive microcomputer and A/D converter, used digital methods exclusively to count spikes and integrate nerve activity. These systems produced accurate and reliable indexes of nerve traffic. The digital system could also be used to store the nerve signal to magnetic disk, thereby allowing the later use of more complex analytical procedures and the possibility of comparing the results of different analyses performed upon a single data set.