Sizing of annuloplasty rings and bands is variably based on intertrigonal or intercommissural distances or estimation of the anterior leaflet area. This studyexamines the results of mitral valve repair with Simplici-T annuloplasty band without predetermining its length in patients with mitral regurgitation (MR) as a result of degenerative disease. Three hundred thirty-seven consecutive patients (median age, 58 years; 69% men) underwent mitral valve repair for MR as a result of degenerative disease (52% bileaflet prolapse and 36% anterior leaflet prolapse). Prolapse of the leaflet was corrected by chordal replacement with Gore-Tex sutures and occasionally a triangular resection. A posterior mitral annuloplasty with a Simplici-T band (median length, 70 mm; range, 52 to 80mm) was performed by securing it from the lateral to the medial fibrous trigones. Annular reduction was performed selectively on the commissures, false commissures, and areas of posterior leaflet resection. Mitral valve function, gradients, and areas were assessed perioperatively and annually during a median follow-up of 4.1years (interquartile range, 2.7 to 5.4 years) and was 98% complete. There were 2 operative and 7 late deaths; survival at 5 years was 97.2%. Three patients were discharged from the hospital with mild to moderate MR, and during follow-up a total of 14 patients had MR greater than mild and 1 patient had MR greater than moderate. Mitral valve re-repair was performed in 1 patient who exhibited mitral stenosis. Freedom from MR greater than mild at 5 years was 93.3%. Selective reduction of the mitral annulus with a posterior band without predetermining its length during mitral valve repair for degenerative MR provides excellent functional results.