The success of a suture is generally linked to its mechanical performance such as tensile strength and knot slippage. The measurement of the tensile properties of sutures suffers from the absence of an international standard test method. In this paper, we present an experimental procedure for the measurement of mechanical parameters and knot slippage of braided sutures made of polyester fibers. The effect of braid angle on tensile and knot performance was studied, and a slippage ratio obtained from load-extension curves was defined. The variation of braid angle had an important influence on breaking load and elongation of the suture. The presence of a knot lowered the breaking load and the rupture occurred consistently at the knot region. The slippage ratio permitted the comparison of the resistance to slippage of different types of knot.