Our review of an entire institutional experience with primary repair of congenital and acquired mitral valve (MV) anomalies in children with concordant atrial-ventricular-arterial connections but without atrioventricular septal defects included 48 patients (1962 to September 1986). Mitral stenosis (MS) was the predominate lesion in 24 patients, mitral incompetence in 22, and mixed in two. Most patients with MS had so-called typical congenital MS (Van Praagh) with abnormalities of all valvular components; virtual or complete absence of chordal development was a consistent finding. Other anatomic substrates (not mutually exclusive) producing MS included supramitral ring with Shone's complex (n = 5), parachute mitral valve (n = 2), hypoplastic mitral ring (n = 3), and rheumatic lesions (n = 3). The anatomic substrates producing mitral incompetence included annular dilatation (n = 16; isolated in seven), leaflet prolapse (n = 7), cleft leaflet (n = 6), leaflet deficiency (n = 3), and rheumatic lesions (n = 2). Concurrent repair of associated lesions was performed in 29 (60%) patients for relief of left ventricular outflow tract obstruction (n = 16) and closure of ventricular septal defects (n = 9; double-outlet right ventricle in three). Six (12.5%) patients had previous repair of coarctation of the aorta. The operative mortality rate was 18.7% (70% confidence limits [CL]; 12.8% to 24.6%), with one death in 35 patients since 1975 (2.9%; 70% CL; 0% to 5.8%). The actuarial freedom from early or late death and reoperation (+/- SEM) was 44.0% +/- 14.8% at 8 years postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)