One or more primary chordae tendineae of the anterior leaflet of the mitral valve was replaced with expanded polytetrafluoroethylene (PTFE) sutures in 22 patients as part of mitral valve reconstructive procedure. One patient with flail anterior leaflet of the tricuspid valve also had replacement of chordae tendineae with a PTFE suture. These patients have been followed from 2 to 48 months, mean of 17 months. Valve function has been assessed annually by Doppler echocardiography. The PTFE chordae cannot be visualized by two- dimensional echocardiography but they seem to allow the leaflet to move normally during the cardiac cycle. The function of the repaired valve in these 23 patients has remained most satisfactory during the observed interval. We believe that PTFE sutures can be used safely to replace diseased chordae tendineae of the mitral and tricuspid valves when conventional techniques of chordal repair are not possible.