The purpose of this study was to examine perceived exertion responses during concentric and eccentric elbow flexor contractions between young adult men and women. Thirty healthy young adults participated in two experimental sessions. During the first session, subjects performed five concentric isokinetic maximal voluntary contractions (MVC) of elbow flexion, followed by nine, randomly-ordered sub-maximal contractions (10-90% MVC). The same procedures were repeated during the second session, with the exception that eccentric contractions were performed. Subjects rated their perceived exertion following the sub-maximal contractions with the Borg category-ratio scale. Perceived exertion was significantly (p<0.05) less than equivalent values on the CR-10 scale at intensities greater than, and equal to, 30% MVC. A three-factor interaction between 30-40% MVC indicated that perceived exertion increased more during the eccentric, than concentric, contractions in women, while the opposite pattern was evident for the men. There were no significant contraction mode or gender differences. Power function modeling revealed that perceived exertion increased in a negatively accelerating manner, except for the men performing eccentric exercise. Perceived exertion increases in a similar non-linear manner between men and women during concentric contractions, while men exhibited a statistically linear pattern during eccentric contractions.