Objective.-To identify the components of exercise rehabilitation programs that were most effective in improving claudication pain symptoms in patients with peripheral arterial disease. Data Sources.-English-language articles were identified by a computer Search using Index Medicus and MEDLINE, followed by an extensive bibliography review. Study Selection.-Studies were included if they provided the mean or individual walking distances or times to the onset of claudication pain and to maximal pain during a treadmill test before and after rehabilitation. Data Extraction.-Walking distances and times and characteristics of the exercise programs were independently abstracted by two observers. Data Synthesis.-Thirty-three English-language studies were identified, of which 21 met the inclusion criteria, Overall, following a program of exercise rehabilitation, the distance (mean+/-SD) to onset of claudication pain increased 179% from 125.9+/-57.3 m to 351.2+/-188.7 m (P<.001), and the distance to maximal claudication pain increased 122% from 325.8+/-148.1 m to 723.3+/-591.5 m (P<.001). The greatest improvement in pain distances occurred with the following exercise program: duration greater than 30 minutes per session, frequency of at least three sessions per week, walking used as the mode of exercise, use of near-maximal pain during training as claudication pain end point, and program length of greater than 6 months, However, the claudication pain end point, program length, and mode of exercise were the only independent predictors (P<.001) for improvement in distances. Conclusions.-The optimal exercise program for improving claudication pain distances in patients with peripheral arterial disease uses intermittent walking to near-maximal pain during a program of at least 6 months. Such a program should be part of the standard medical care for patients with intermittent claudication.