This study determined whether persons with coronary risk factors have increased fatigue during or after exercise. Ratings of perceived exertion were first shown to be a valid measure of fatigue; i.e., ratings of perceived exertion correlated with heart rate both during and after exercise and at each of three exercise tests (all within-subjects r greater than 0.88). Physical inactivity and smoking were associated with increased fatigue. Inactive men and smokers had higher levels of fatigue during both exercise and recovery conditions and at each of three exercise test. The increased fatigue of men who were inactive and smoked was not entirely due to their lower level of fitness. The risk factors of age, Type A behavior pattern, blood pressure, serum cholesterol, serum high-density lipoprotein, and obesity were not associated with increased fatigue. The increased fatigue experienced by inactive persons and smokers may account for their decreased compliance to exercise programs.