Expanded PTFE (ePTFE) sutures have been used widely as a mitral chordal substitute. We present a structural analysis of ePTFE sutures implanted as an artificial chordae for 7.5 years and 8.6 years in patients with mitral regurgitation. No calcification was found either macroscopically or microscopically, and the ePTFE suture retained its normal flexibility. The suture was totally encapsulated with host tissues composed of dense fibrous tissue covered with endothelial cells.