The purpose of this study was to determine the reliability of a protocol to assess reflex activation history in the vastus medialis. Eight subjects reported to the laboratory on two occasions. Reflex activation history was assessed by delivering two stimuli of the same intensity 80 ms apart. The dependent variable evaluated was the percentage of the unconditioned reflex amplitude. Eight trials were elicited and averaged on each day. An intraclass correlation coefficient (ICC 2,1) was used to estimate intersession reliability. The ICC for the protocol was found to be 0.9647. The results of this investigation indicate that this technique can reliably estimate reflex activation history in the vastus medialis.