The surgical attack upon acquired heart disease has progressed at a rapid pace since the advent of mitral commissurotomy in 1949.1The outstanding valvular defect, which still is unsolved from a surgical standpoint, is mitral insufficiency. Bailey2found at operation that 21.7% of patients operated upon for mitral stenosis had a significant amount of mitral insufficiency. In addition, in 5.5% of these patients the insufficiency was the major lesion. The surgical attack on this lesion has been varied. The sling procedure, which was the first clinical approach, has now been discarded.3Prosthetic alleviation of the insufficiency by the use of a plastic baffle, as advocated by Harken,4is probably the most accepted clinical method today, along with the suturing of the valve as has been advocated by Bailey and co-workers.5Experimentally the mitral valve has been replaced by a polymerized methyl methacrylate (Lucite) prosthesis by