Despite many successes with teleoperated robotic surgical systems, some surgeons feel that the lack of haptic (force or tactile) feedback is detrimental in applications requiring fine suture manipulation. In this paper, we study the difference between applied suture forces in three knot tying exercises: hand ties, instrument ties (using needle drivers), and robot ties (using the da Vinci™ Surgical System from Intuitive Surgical, Inc.). Both instrument and robot-assisted ties differ from hand ties in accuracy of applied force. However, only the robot ties differ from hand ties in repeatability of applied force. Furthermore, comparison between attendings and residents revealed statistically significant differences in the forces used during hand ties, although attendings and residents perform similarly when comparing instrument and robot ties to hand ties. These results indicate that resolved force feedback would improve robot-assisted performance during complex surgical tasks such as knot tying with fine suture.