Prolapsed leaflet is the result of ruptured chordae, elongated chordae, or ruptured papillary muscle. Various techniques adapted to each of these lesions were developed, and repair of 213 prolapsed mitral valves was performed between 1969 and 1977. There were 109 patients with ruptured chordae treated by quadrangular resection of the prolapsed leaflet; 103 patients with elongated chordae were treated by either a "sliding plasty" of the papillary muscle or a "shortening plasty" of the chordae; and 1 patient with ruptured papillary muscle was treated by reimplantation. The great majority of patients had an associated annular dilatation or deformation requiring the use of a Carpentier ring to remodel the annulus and reinforce the repair. The operative mortality was 4% and the late mortality, 3%. There were 6 reoperations, 3 of which occurred within 1 year. Thromboembolic complications occurred in only 1 patient (0.5%), even though the majority of patients received no anticoagulation treatment. Actuarial curves demonstrated a 91% survival at 8 years.