This study compared self-ratings of components of physical fitness with objective measures of physical fitness. We made comparisons in two groups of male infantry soldiers (n = 96 and n = 276) and one group of older male military officers (n = 241). To obtain self-ratings of physical fitness, we asked subjects, "Compared to others of your age and sex, how would you rate your (a) endurance, (b) sprint speed, (c) strength, (d) flexibility?" Subjects responded to each of the four questions on a five-point scale. Self-ratings of endurance were systematically related to three measures of aerobic capacity, including VO2max, peak VO2, and two-mile run time (r = 0.29 to 0.53). Self-ratings of sprint speed showed only weak relationships to measures of anaerobic capacity assessed by the Wingate test, push-ups, and sit-ups (r = 0.10 to 0.17). Strength ratings were systematically related to measures of maximal strength (r = 0.28 to 0.53). Upper body strength measures were more closely associated with the self-ratings of strength than were measures of lower body strength. Responses to the flexibility question were systematically related to measures of hip/low back flexibility (r = 0.30 and 0.48) but not to other measures of flexibility. Apparently, physically active subjects can approximately classify their aerobic capacity, muscle strength, and some types of flexibility.