Force feedback is widely assumed to enhance performance in robotic surgery, but its benefits have not yet been systematically assessed. In this study we examine the effects of force feedback on a blunt dissection task. Twenty subjects used a telerobotic system to expose an artery in a synthetic model while viewing the operative site with a video laparoscope. Subjects were drawn from a range of surgical backgrounds, from inexperienced to attending surgeons. Performance was compared between three force feedback gains: 0% (no force feedback), 37%, and 75%. The absence of force feedback increased the average force magnitude applied to the tissue by at least 50%, and increased the peak force magnitude by at least 100%. The number of errors that damage tissue increased by over a factor of 3. The rate and precision of dissection were not significantly enhanced with force feedback. These results hold across all levels of previous surgical experience. We hypothesize that force feedback is helpful in this blunt dissection task because the artery is stiffer than the surrounding tissue. This mechanical contrast serves to constrain the subject's hand from commanding inappropriate motions that generate large forces.