One hundred and twenty patients with chronic lateral epicondylitis were randomized to undergo a 3-month home-based eccentric or concentric graded exercise regimen. The purpose of this study was to compare the impact of eccentric versus concentric exercise on elbow pain and function up to 12 months post-intervention. Eccentric graded exercise reduced pain and increased muscle strength more effectively than concentric graded exercise, but crude differences were not significant at final follow-up. Function and quality of life measures were similar between groups throughout the follow-up period.