The purpose of this study was to determine the biomechanical characteristics of 16 arthroscopic knots and to determine if locking knots have superior loop security compared to non-locking knots. Sixteen knot types were tied in arthroscopic fashion and tested on a materials testing system. Knots were cyclically loaded to 30 Newtons (N) for 20 cycles and then loaded to failure at 1.25 mm/s. Ten samples of each knot were tied using both #2 Ethibond and #1 PDS II. Load to ultimate failure, load to clinical failure, post-cyclic stiffness, cyclical elongation, ultimate displacement, loop security, and mode of failure were determined for each knot. Nicky's Knot and the French Knot were most consistently ranked within the top five knot types for each of the biomechanical parameters. Locking knots did not improve loop security over non-locking knots.