The purpose of this study was to explore high school students' perceived exertion after participating in the Progressive Aerobic Cardiovascular Endurance Run (PACER). Immediately after completing the PACER, students (N = 792) indicated their perceived exertion on the OMNI rating of perceived exertion (RPE) for children (1-10 scale). All students, whether passing or failing, rated their exertion after the PACER test significantly lower than a hypothetical mean of 6 (p less than 0.05), which corresponds to "tired" on the OMNI scale. Students who did not meet the criteria rated their exertion less than tired and may not have provided a full effort on the test, which resulted in less than acceptable passing rates for cardiovascular fitness among this population. (Contains 1 table and 2 figures.)