Unguarded mitral orifice (UMO) is an extremely rare congenital cardiac anomaly characterized by the complete absence of mitral valvar leaflets and tensor apparatus (chordae tendineae and papillary muscles) at the mitral annulus and severe thinning of the left ventricular (LV) free wall [ 1 Yasukochi S. Satomi G. Park I. Ando M. Momma K. Unguarded mitral orifice, mirror-imaged atrial arrangement, and discordant atrioventricular connections. Cardiol Young. 1999; 9: 478-483 PubMed Google Scholar , 2 Earing M.G. Edwards W.D. Puga F.J. Cabalka A.K. Unguarded mitral orifice associated with discordant atrioventricular connection, double-outlet right ventricle, and pulmonary atresia. Pediatr Cardiol. 2003; 24: 490-492 Crossref PubMed Scopus (6) Google Scholar ]. To our knowledge, only 3 cases have been reported [ 1 Yasukochi S. Satomi G. Park I. Ando M. Momma K. Unguarded mitral orifice, mirror-imaged atrial arrangement, and discordant atrioventricular connections. Cardiol Young. 1999; 9: 478-483 PubMed Google Scholar , 2 Earing M.G. Edwards W.D. Puga F.J. Cabalka A.K. Unguarded mitral orifice associated with discordant atrioventricular connection, double-outlet right ventricle, and pulmonary atresia. Pediatr Cardiol. 2003; 24: 490-492 Crossref PubMed Scopus (6) Google Scholar ]. We report here the possible fourth case occurring in the setting of double-outlet right ventricle (DORV) {I, D, D} (visceroatrial situs inversus [I], D-loop ventricles [D], and D-malposition of the great arteries [D]) associated with pulmonary atresia, i.e. atrioventricular discordance associated with DORV and pulmonary atresia in situs inversus. Unexpectedly, all 4 cases, including ours, were male, and all had the identical, above-mentioned segmental set and alignment (DORV {I, D, D}) and similar associated malformations (pulmonary atresia or stenosis) [ 1 Yasukochi S. Satomi G. Park I. Ando M. Momma K. Unguarded mitral orifice, mirror-imaged atrial arrangement, and discordant atrioventricular connections. Cardiol Young. 1999; 9: 478-483 PubMed Google Scholar , 2 Earing M.G. Edwards W.D. Puga F.J. Cabalka A.K. Unguarded mitral orifice associated with discordant atrioventricular connection, double-outlet right ventricle, and pulmonary atresia. Pediatr Cardiol. 2003; 24: 490-492 Crossref PubMed Scopus (6) Google Scholar ]. Therefore, these limited case series might imply that the consistent association of 2 uncommon anomalies—UMO and DORV {I, D, D} with pulmonary atresia/stenosis—represents a previously unsuspected causal relation and possibly constitutes a new constellation of defects with unique clinical implications.