The results of anterior mitral leaflet repair were evaluated by the serial change of mitral regurgitation (MR) using transesophageal echocardiography (TEE) in 24 patients undergoing mitral valve repair for anterior leaflet prolapse during 1988 to 1994, who were examined by TEE immediately after operation, 1 month after operation, and late after operation (mean 15 months). Chordal replacement using polytetra-fluorethylene chordae was performed in 15 patients (PTFE group), and not performed in 9 patients (non-PTFE group). MR jet area late after operation was significantly smaller in the PTFE group than in the non-PTFE group (2.2 +/- 2.3 vs. 4.6 +/- 2.3 cm2, p < 0.05). Moderate to severe MR was observed in four patients (27%) in the PTFE group, and six (67%) in the non-PTFE group late after operation. The thickness of the mitral leaflet before operation was more than 5 mm in all patients with more than moderate MR late after operation in the PTFE group. Chordal replacement using polytetrafluorethylene chordae showed better results compared with conventional mitral valve repair without polytetrafluorethylene chordae over the follow-up period of 15 months.