Two terpenic constituents, E,E,-alpha-farnesene and E-beta-farnesene, were found to be elevated in dominant male urine when compared to subordinate or control males. These two urinary compounds were absent in the bladder urine of males; however, they were the most prominent constituents of the perputial gland's aliquots. The results of a two-choice preference test, conducted on ICR/Alb subordinate males, gave a strong indication that these two terpenic constituents introduced into the previously attractive stimulus significantly discouraged prolonged investigations by male mice. The compounds, whether present in the urine matrix or water, rendered the stimulus with a quality behaviorally similar to the urine of dominant males. It appears that they may be synonymous with the previously described aversion signal produced by dominant males. We suggest that these compounds may play a wide-ranging role in the territorial marking behavior of male mice.